From bc8b9edc0860f4804dfd0ea868ee7beaa564e62a Mon Sep 17 00:00:00 2001
From: DJ O'Leary <dijitol@proton.me>
Date: Sat, 27 Jun 2026 04:28:48 +0200
Subject: test: fix ocaml tests 2024 {WIP}

---
 2024/ocaml/.envrc                        |   1 -
 2024/ocaml/.gitignore                    |  29 ------
 2024/ocaml/.ocamlformat                  |   2 -
 2024/ocaml/AoC_2024.opam                 |  32 -------
 2024/ocaml/README.md                     |  21 -----
 2024/ocaml/Taskfile.yml                  |  56 ------------
 2024/ocaml/bin/dune                      |   5 -
 2024/ocaml/bin/main.ml                   |  46 ----------
 2024/ocaml/dune-project                  |  28 ------
 2024/ocaml/flake.lock                    |  27 ------
 2024/ocaml/flake.nix                     |  44 ---------
 2024/ocaml/lib/day_01/part_01.ml         |  40 --------
 2024/ocaml/lib/day_01/part_02.ml         |  44 ---------
 2024/ocaml/lib/day_02/part_01.ml         |  42 ---------
 2024/ocaml/lib/day_03/part_01.ml         |  33 -------
 2024/ocaml/lib/day_04/part_01.ml         |  85 -----------------
 2024/ocaml/lib/day_05/part_01.ml         |  62 -------------
 2024/ocaml/lib/dune                      |   5 -
 2024/ocaml/lib/file/read_input.ml        |  11 ---
 2024/ocaml/lib/grid/cell.ml              |  18 ----
 2024/ocaml/lib/grid/cell.mli             |  18 ----
 2024/ocaml/lib/grid/grid.ml              |  14 ---
 2024/ocaml/lib/grid/grid.mli             |   6 --
 2024/ocaml/test/day_01_part_01.ml        |  27 ------
 2024/ocaml/test/day_01_part_02.ml        |  17 ----
 2024/ocaml/test/day_02_part_01.ml        |  38 --------
 2024/ocaml/test/day_03_part_01.ml        |  29 ------
 2024/ocaml/test/day_04_part_01.ml        | 151 -------------------------------
 2024/ocaml/test/day_05_part_01.ml        |   4 -
 2024/ocaml/test/dune                     |  10 --
 2024/ocaml/test/grid.ml                  |   5 -
 ocaml/README.md                          |  20 ++++
 ocaml/flake.nix                          |   3 +-
 ocaml/lib/year2024/day01/part01.ml       |  40 ++++++++
 ocaml/lib/year2024/day01/part02.ml       |  44 +++++++++
 ocaml/lib/year2024/day02/part01.ml       |  42 +++++++++
 ocaml/lib/year2024/day03/part01.ml       |  33 +++++++
 ocaml/lib/year2024/day04/part01.ml       |  85 +++++++++++++++++
 ocaml/lib/year2024/day05/part01.ml       |  64 +++++++++++++
 ocaml/lib/year2024/dune                  |   5 +
 ocaml/test/year2024/day01/dune           |  11 +++
 ocaml/test/year2024/day01/test_part01.ml |  30 ++++++
 ocaml/test/year2024/day01/test_part02.ml |  16 ++++
 ocaml/test/year2024/day02/dune           |  10 ++
 ocaml/test/year2024/day02/test_part01.ml |  41 +++++++++
 ocaml/test/year2024/day03/dune           |  10 ++
 ocaml/test/year2024/day03/test_part01.ml |  29 ++++++
 ocaml/test/year2024/day04/dune           |  10 ++
 ocaml/test/year2024/day04/test_part01.ml | 141 +++++++++++++++++++++++++++++
 49 files changed, 633 insertions(+), 951 deletions(-)
 delete mode 100644 2024/ocaml/.envrc
 delete mode 100644 2024/ocaml/.gitignore
 delete mode 100644 2024/ocaml/.ocamlformat
 delete mode 100644 2024/ocaml/AoC_2024.opam
 delete mode 100644 2024/ocaml/README.md
 delete mode 100644 2024/ocaml/Taskfile.yml
 delete mode 100644 2024/ocaml/bin/dune
 delete mode 100644 2024/ocaml/bin/main.ml
 delete mode 100644 2024/ocaml/dune-project
 delete mode 100644 2024/ocaml/flake.lock
 delete mode 100644 2024/ocaml/flake.nix
 delete mode 100644 2024/ocaml/lib/day_01/part_01.ml
 delete mode 100644 2024/ocaml/lib/day_01/part_02.ml
 delete mode 100644 2024/ocaml/lib/day_02/part_01.ml
 delete mode 100644 2024/ocaml/lib/day_03/part_01.ml
 delete mode 100644 2024/ocaml/lib/day_04/part_01.ml
 delete mode 100644 2024/ocaml/lib/day_05/part_01.ml
 delete mode 100644 2024/ocaml/lib/dune
 delete mode 100644 2024/ocaml/lib/file/read_input.ml
 delete mode 100644 2024/ocaml/lib/grid/cell.ml
 delete mode 100644 2024/ocaml/lib/grid/cell.mli
 delete mode 100644 2024/ocaml/lib/grid/grid.ml
 delete mode 100644 2024/ocaml/lib/grid/grid.mli
 delete mode 100644 2024/ocaml/test/day_01_part_01.ml
 delete mode 100644 2024/ocaml/test/day_01_part_02.ml
 delete mode 100644 2024/ocaml/test/day_02_part_01.ml
 delete mode 100644 2024/ocaml/test/day_03_part_01.ml
 delete mode 100644 2024/ocaml/test/day_04_part_01.ml
 delete mode 100644 2024/ocaml/test/day_05_part_01.ml
 delete mode 100644 2024/ocaml/test/dune
 delete mode 100644 2024/ocaml/test/grid.ml
 create mode 100644 ocaml/lib/year2024/day01/part01.ml
 create mode 100644 ocaml/lib/year2024/day01/part02.ml
 create mode 100644 ocaml/lib/year2024/day02/part01.ml
 create mode 100644 ocaml/lib/year2024/day03/part01.ml
 create mode 100644 ocaml/lib/year2024/day04/part01.ml
 create mode 100644 ocaml/lib/year2024/day05/part01.ml
 create mode 100644 ocaml/lib/year2024/dune
 create mode 100644 ocaml/test/year2024/day01/dune
 create mode 100644 ocaml/test/year2024/day01/test_part01.ml
 create mode 100644 ocaml/test/year2024/day01/test_part02.ml
 create mode 100644 ocaml/test/year2024/day02/dune
 create mode 100644 ocaml/test/year2024/day02/test_part01.ml
 create mode 100644 ocaml/test/year2024/day03/dune
 create mode 100644 ocaml/test/year2024/day03/test_part01.ml
 create mode 100644 ocaml/test/year2024/day04/dune
 create mode 100644 ocaml/test/year2024/day04/test_part01.ml

diff --git a/2024/ocaml/.envrc b/2024/ocaml/.envrc
deleted file mode 100644
index 3550a30..0000000
--- a/2024/ocaml/.envrc
+++ /dev/null
@@ -1 +0,0 @@
-use flake
diff --git a/2024/ocaml/.gitignore b/2024/ocaml/.gitignore
deleted file mode 100644
index a18e084..0000000
--- a/2024/ocaml/.gitignore
+++ /dev/null
@@ -1,29 +0,0 @@
-*.annot
-*.cmo
-*.cma
-*.cmi
-*.a
-*.o
-*.cmx
-*.cmxs
-*.cmxa
-
-# ocamlbuild working directory
-_build/
-
-# ocamlbuild targets
-*.byte
-*.native
-
-# oasis generated files
-setup.data
-setup.log
-
-# Merlin configuring file for Vim and Emacs
-.merlin
-
-# Dune generated files
-*.install
-
-# Local OPAM switch
-_opam/
diff --git a/2024/ocaml/.ocamlformat b/2024/ocaml/.ocamlformat
deleted file mode 100644
index 912bea4..0000000
--- a/2024/ocaml/.ocamlformat
+++ /dev/null
@@ -1,2 +0,0 @@
-profile = default
-version = 0.27.0
diff --git a/2024/ocaml/AoC_2024.opam b/2024/ocaml/AoC_2024.opam
deleted file mode 100644
index 6be14e1..0000000
--- a/2024/ocaml/AoC_2024.opam
+++ /dev/null
@@ -1,32 +0,0 @@
-# This file is generated by dune, edit dune-project instead
-opam-version: "2.0"
-synopsis: "Advent of Code 2024"
-description: "Solutions to the Advent of Code puzzles for 2024"
-maintainer: ["D.J. O'Leary"]
-authors: ["D.J. O'Leary"]
-license: "Unlicense"
-tags: ["aoc2024" "Advent of Code 2024"]
-homepage: "https://github.com/DJOLEARY/Advent_of_Code"
-doc:
-  "https://github.com/DJOLEARY/Advent_of_Code/blob/main/2024/OCaml/README.md"
-bug-reports: "https://github.com/DJOLEARY/Advent_of_Code/issues"
-depends: [
-  "ocaml"
-  "dune" {>= "3.16"}
-  "odoc" {with-doc}
-]
-build: [
-  ["dune" "subst"] {dev}
-  [
-    "dune"
-    "build"
-    "-p"
-    name
-    "-j"
-    jobs
-    "@install"
-    "@runtest" {with-test}
-    "@doc" {with-doc}
-  ]
-]
-dev-repo: "git+https://github.com/DJOLEARY/Advent_of_Code.git"
diff --git a/2024/ocaml/README.md b/2024/ocaml/README.md
deleted file mode 100644
index caa88fe..0000000
--- a/2024/ocaml/README.md
+++ /dev/null
@@ -1,21 +0,0 @@
-# OCaml 2024
-
-## Getting Started
-
-### How to Build
-
-```sh
-task build
-```
-
-### How to Run
-
-```sh
-task run
-```
-
-### How to Test
-
-```sh
-task test
-```
diff --git a/2024/ocaml/Taskfile.yml b/2024/ocaml/Taskfile.yml
deleted file mode 100644
index 1d8a89e..0000000
--- a/2024/ocaml/Taskfile.yml
+++ /dev/null
@@ -1,56 +0,0 @@
-# https://taskfile.dev
-
-version: "3"
-vars:
-  PROJECT_NAME: AoC_2024
-tasks:
-  default:
-    desc: Prints this message
-    cmds:
-      - cmd: task --list-all
-  build:doc:
-    desc: Builds documentation using ocamldoc
-    preconditions:
-      - which ocamldoc
-    cmds:
-      - cmd: ocamldoc -html -d docs bin/main.ml
-    silent: true
-  build:
-    desc: Builds the project
-    preconditions:
-      - which dune
-    cmds:
-      - cmd: dune build
-  test:
-    desc: Runs the tests in the 'tests' directory
-    ignore_error: true
-    env:
-      OUNIT_CI: true
-    preconditions:
-      - which dune
-    deps:
-      - task: build
-    cmds:
-      - cmd: dune test {{.CLI_ARGS}}
-  test:watch:
-    desc: Continuously runs the tests in the 'tests' directory
-    ignore_error: true
-    sources:
-      - lib/**/*.ml
-      - test/**/*.ml
-    env:
-      OUNIT_CI: true
-    preconditions:
-      - which dune
-    deps:
-      - task: build
-    cmds:
-      - cmd: dune test --watch {{.CLI_ARGS}}
-  run:
-    desc: Runs the project
-    preconditions:
-      - which dune
-    deps:
-      - task: build
-    cmds:
-      - cmd: dune exec {{.PROJECT_NAME}}
diff --git a/2024/ocaml/bin/dune b/2024/ocaml/bin/dune
deleted file mode 100644
index ee36b46..0000000
--- a/2024/ocaml/bin/dune
+++ /dev/null
@@ -1,5 +0,0 @@
-(executable
- (public_name AoC_2024)
- (name main)
- (modes byte exe)
- (libraries AoC_2024))
diff --git a/2024/ocaml/bin/main.ml b/2024/ocaml/bin/main.ml
deleted file mode 100644
index a76e046..0000000
--- a/2024/ocaml/bin/main.ml
+++ /dev/null
@@ -1,46 +0,0 @@
-open AoC_2024
-
-let day_to_path day =
-  let string_day = string_of_int day in
-  let formatted_day = if day < 10 then "0" ^ string_day else string_day in
-  "../_input/day_" ^ formatted_day ^ ".txt"
-
-let print_solution day_num part_num answer =
-  print_string "D";
-  print_int day_num;
-  print_string ":P";
-  print_int part_num;
-  print_string " -> ";
-  print_int answer;
-  print_newline ()
-
-let day_1 =
-  let lines = File.Read_input.lines_from_file (day_to_path 1) in
-  let left, right = Day_01.Part_01.lines_to_lists lines in
-  let part_01 = Day_01.Part_01.solve left right in
-  print_solution 1 1 part_01;
-  let part_02 = Day_01.Part_02.solve left right in
-  print_solution 1 2 part_02
-
-let day_2 =
-  let lines = File.Read_input.lines_from_file (day_to_path 2) in
-  let reports = Day_02.Part_01.lines_to_reports lines in
-  let part_01 = Day_02.Part_01.solve reports in
-  print_solution 2 1 part_01
-
-let day_3 =
-  let lines = File.Read_input.lines_from_file (day_to_path 3) in
-  let line = List.fold_left (fun acc line -> acc ^ line) "" lines in
-  let part_01 = Day_03.Part_01.solve line in
-  print_solution 3 1 part_01
-
-let day_4 =
-  let lines = File.Read_input.lines_from_file (day_to_path 4) in
-  let part_01 = Day_04.Part_01.solve lines in
-  print_solution 4 1 part_01
-
-let _ =
-  day_1;
-  day_2;
-  day_3;
-  day_4
diff --git a/2024/ocaml/dune-project b/2024/ocaml/dune-project
deleted file mode 100644
index 3f3a7bc..0000000
--- a/2024/ocaml/dune-project
+++ /dev/null
@@ -1,28 +0,0 @@
-(lang dune 3.16)
-
-(name AoC_2024)
-
-(generate_opam_files true)
-
-(source
- (github DJOLEARY/Advent_of_Code))
-
-(authors "D.J. O'Leary")
-
-(maintainers "D.J. O'Leary")
-
-(license Unlicense)
-
-(documentation https://github.com/DJOLEARY/Advent_of_Code/blob/main/2024/OCaml/README.md)
-
-(map_workspace_root false)
-
-(package
- (name AoC_2024)
- (synopsis "Advent of Code 2024")
- (description "Solutions to the Advent of Code puzzles for 2024")
- (depends ocaml dune)
- (tags
-  (aoc2024 "Advent of Code 2024")))
-
-; See the complete stanza docs at https://dune.readthedocs.io/en/stable/reference/dune-project/index.html
diff --git a/2024/ocaml/flake.lock b/2024/ocaml/flake.lock
deleted file mode 100644
index b7695d9..0000000
--- a/2024/ocaml/flake.lock
+++ /dev/null
@@ -1,27 +0,0 @@
-{
-  "nodes": {
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1741010256,
-        "narHash": "sha256-WZNlK/KX7Sni0RyqLSqLPbK8k08Kq7H7RijPJbq9KHM=",
-        "owner": "nixos",
-        "repo": "nixpkgs",
-        "rev": "ba487dbc9d04e0634c64e3b1f0d25839a0a68246",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nixos",
-        "ref": "nixos-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "nixpkgs": "nixpkgs"
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}
diff --git a/2024/ocaml/flake.nix b/2024/ocaml/flake.nix
deleted file mode 100644
index 74a5dc6..0000000
--- a/2024/ocaml/flake.nix
+++ /dev/null
@@ -1,44 +0,0 @@
-{
-  description = "Advent of Code 2024: OCaml";
-
-  inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
-  };
-
-  outputs =
-    { nixpkgs, ... }:
-    let
-      pkgs = nixpkgs.legacyPackages.x86_64-linux;
-    in
-    {
-      devShells.x86_64-linux.default =
-        let
-          ocamlPackages = pkgs.ocaml-ng.ocamlPackages_5_2;
-        in
-        pkgs.mkShell {
-          # build tools
-          nativeBuildInputs = with ocamlPackages; [
-            pkgs.opam
-            ocaml
-            findlib
-            dune_3
-          ];
-          # dependencies
-          buildInputs = with ocamlPackages; [
-            bisect_ppx
-            findlib
-            menhir
-            ocaml-lsp
-            earlybird
-            ocamlformat
-            ocamlgraph
-            odoc
-            ounit2
-            re2
-            utop
-
-            pkgs.gh # GitHub CLI
-          ];
-        };
-    };
-}
diff --git a/2024/ocaml/lib/day_01/part_01.ml b/2024/ocaml/lib/day_01/part_01.ml
deleted file mode 100644
index 100b12a..0000000
--- a/2024/ocaml/lib/day_01/part_01.ml
+++ /dev/null
@@ -1,40 +0,0 @@
-(* Day 1: Part 1 *)
-
-let calculate_distance x y = Stdlib.abs (x - y)
-
-(** Require: left and right to be the same length *)
-let solve left right =
-  let sorted_left = List.sort Stdlib.compare left in
-  let sorted_right = List.sort Stdlib.compare right in
-  let distances = List.map2 calculate_distance sorted_left sorted_right in
-  List.fold_left ( + ) 0 distances
-
-let left line =
-  let pos = 0 in
-  let len = String.index line ' ' in
-  String.sub line pos len
-
-let right line =
-  let pos = String.rindex line ' ' + 1 in
-  let len = String.length line - pos in
-  String.sub line pos len
-
-let line_to_tuple line = (left line, right line)
-
-let lines_to_lists lines =
-  let tuples = List.map line_to_tuple lines in
-  let left =
-    List.map
-      (fun t ->
-        let l, _ = t in
-        int_of_string l)
-      tuples
-  in
-  let right =
-    List.map
-      (fun t ->
-        let _, r = t in
-        int_of_string r)
-      tuples
-  in
-  (left, right)
diff --git a/2024/ocaml/lib/day_01/part_02.ml b/2024/ocaml/lib/day_01/part_02.ml
deleted file mode 100644
index 25c8b7d..0000000
--- a/2024/ocaml/lib/day_01/part_02.ml
+++ /dev/null
@@ -1,44 +0,0 @@
-(* Day 1: Part 2 *)
-
-let rec count_occurrances_help element acc lst =
-  match lst with
-  | [] -> acc
-  | h :: t ->
-      if h = element then count_occurrances_help element (acc + 1) t
-      else count_occurrances_help element acc t
-
-let count_occurrances element lst = count_occurrances_help element 0 lst
-
-let solve left right =
-  List.map (fun x -> x * count_occurrances x right) left
-  |> List.fold_left ( + ) 0
-
-let left line =
-  let pos = 0 in
-  let len = String.index line ' ' in
-  String.sub line pos len
-
-let right line =
-  let pos = String.rindex line ' ' + 1 in
-  let len = String.length line - pos in
-  String.sub line pos len
-
-let line_to_tuple line = (left line, right line)
-
-let lines_to_lists lines =
-  let tuples = List.map line_to_tuple lines in
-  let left =
-    List.map
-      (fun t ->
-        let l, _ = t in
-        int_of_string l)
-      tuples
-  in
-  let right =
-    List.map
-      (fun t ->
-        let _, r = t in
-        int_of_string r)
-      tuples
-  in
-  (left, right)
diff --git a/2024/ocaml/lib/day_02/part_01.ml b/2024/ocaml/lib/day_02/part_01.ml
deleted file mode 100644
index 32d7ab8..0000000
--- a/2024/ocaml/lib/day_02/part_01.ml
+++ /dev/null
@@ -1,42 +0,0 @@
-(* Day 2: Part 1 *)
-
-type level = int
-type reports = level list list
-
-let rec compare_report_levels_helper comparison prev report =
-  match report with
-  | [] -> true
-  | h :: t -> comparison prev h && compare_report_levels_helper comparison h t
-
-let compare_report_levels comparison report =
-  match report with
-  | [] -> true
-  | h :: t -> compare_report_levels_helper comparison h t
-
-let all_increasing report = compare_report_levels ( < ) report
-let all_decreasing report = compare_report_levels ( > ) report
-
-let at_least_one report =
-  compare_report_levels (fun prev curr -> prev <> curr) report
-
-let at_most_three report =
-  compare_report_levels (fun prev curr -> abs (prev - curr) <= 3) report
-
-let check_report_safety report =
-  if not (all_increasing report || all_decreasing report) then false
-  else if not (at_least_one report && at_most_three report) then false
-  else true
-
-let rec count_safe_reports acc lst =
-  match lst with
-  | [] -> acc
-  | h :: t ->
-      if h then count_safe_reports (acc + 1) t else count_safe_reports acc t
-
-let solve reports =
-  reports |> List.map check_report_safety |> count_safe_reports 0
-
-let line_to_report line =
-  line |> String.split_on_char ' ' |> List.map int_of_string
-
-let lines_to_reports lines = List.map line_to_report lines
diff --git a/2024/ocaml/lib/day_03/part_01.ml b/2024/ocaml/lib/day_03/part_01.ml
deleted file mode 100644
index c12b68a..0000000
--- a/2024/ocaml/lib/day_03/part_01.ml
+++ /dev/null
@@ -1,33 +0,0 @@
-(* Day 3: Part 1 *)
-
-let find_mul text =
-  let regex_or_err = Re2.create "mul\\(([0-9]{1,3}),([0-9]{1,3})\\)" in
-  match regex_or_err with
-  | Ok regex -> (
-      let matches = Re2.get_matches regex text in
-      match matches with Ok matches -> matches | Error _ -> [])
-  | Error _ -> []
-
-let extract_pairs (matches : Re2.Match.t list) : (int * int) list =
-  List.map
-    (fun x ->
-      let left = Re2.Match.get x ~sub:(`Index 1) in
-      match left with
-      | None -> (0, 0)
-      | Some left -> (
-          let left_num = int_of_string left in
-          let right = Re2.Match.get x ~sub:(`Index 2) in
-          match right with
-          | None -> (0, 0)
-          | Some right ->
-              let right_num = int_of_string right in
-              (left_num, right_num)))
-    matches
-
-let solve input =
-  input |> find_mul |> extract_pairs
-  |> List.fold_left
-       (fun acc pair ->
-         let left, right = pair in
-         acc + (left * right))
-       0
diff --git a/2024/ocaml/lib/day_04/part_01.ml b/2024/ocaml/lib/day_04/part_01.ml
deleted file mode 100644
index acb3e3b..0000000
--- a/2024/ocaml/lib/day_04/part_01.ml
+++ /dev/null
@@ -1,85 +0,0 @@
-(* Day 4: Part 1 *)
-
-type character = { index : int; character : char }
-type direction = N | NE | E | SE | S | SW | W | NW
-
-let all_directions = [ N; NE; E; SE; S; SW; W; NW ]
-let needle = "XMAS"
-
-(** [calculate_row_offset lines] is the offset used to move between the rows of
-    the concatenated variant of [lines] as though it were a grid. Requires:
-    values of [lines] all have the same length *)
-let calculate_row_offset lines =
-  match lines with [] -> 0 | h :: _ -> String.length h
-
-let join_lines lines =
-  let concat_trim acc line = acc ^ String.trim line in
-  List.fold_left concat_trim "" lines
-
-let explode s = List.init (String.length s) (String.get s)
-let is_in_bounds length index = index >= 0 && index < length
-
-let get_at_index line index =
-  let length = String.length line in
-  if not (is_in_bounds length index) then "."
-  else
-    let character = String.get line index in
-    Char.escaped character
-
-let get_direction_index row_offset direction index =
-  match direction with
-  | N -> index - row_offset
-  | NE -> index - row_offset + 1
-  | E -> index + 1
-  | SE -> index + row_offset + 1
-  | S -> index + row_offset
-  | SW -> index + row_offset - 1
-  | W -> index - 1
-  | NW -> index - row_offset - 1
-
-let get_direction_string get_char get_offset_index index =
-  let first = get_char index in
-  let second_index = get_offset_index index in
-  let second = get_char second_index in
-  let third_index = get_offset_index second_index in
-  let third = get_char third_index in
-  let fourth_index = get_offset_index third_index in
-  let fourth = get_char fourth_index in
-  first ^ second ^ third ^ fourth
-
-let check_direction get_from_line get_offset_index index direction =
-  get_direction_string get_from_line (get_offset_index direction) index = needle
-
-let calculate_num_of_matches line row_offset character =
-  let get_from_line_at_index = get_at_index line in
-  let get_offset_direction_index = get_direction_index row_offset in
-  let check_direction_from_index =
-    check_direction get_from_line_at_index get_offset_direction_index
-      character.index
-  in
-  all_directions
-  |> List.map check_direction_from_index
-  |> List.map (fun x -> match x with true -> 1 | false -> 0)
-  |> List.fold_left ( + ) 0
-
-(* Tried:
-   2544 -> too high
-   1272 (previous halved) -> too low *)
-let solve lines =
-  let row_offset = calculate_row_offset lines in
-  let line = join_lines lines in
-  let chars = explode line in
-  let characters = List.mapi (fun i c -> { index = i; character = c }) chars in
-  let xs =
-    List.filter
-      (fun c -> match c.character with 'X' -> true | _ -> false)
-      characters
-  in
-  let calculate_num_of_surrounding_matches_in_line =
-    calculate_num_of_matches line row_offset
-  in
-  let num_of_matches =
-    List.map calculate_num_of_surrounding_matches_in_line xs
-    |> List.fold_left ( + ) 0
-  in
-  num_of_matches
diff --git a/2024/ocaml/lib/day_05/part_01.ml b/2024/ocaml/lib/day_05/part_01.ml
deleted file mode 100644
index f32bef1..0000000
--- a/2024/ocaml/lib/day_05/part_01.ml
+++ /dev/null
@@ -1,62 +0,0 @@
-(* Day 5: Part 1 *)
-
-module StringMap = Map.Make (String)
-
-let inverse_page_rule page_rule =
-  String.split_on_char '|' page_rule |> fun lst ->
-  match lst with [] -> "" | _ :: _ -> String.concat "|" (List.rev lst)
-
-(** [parse_aux acc page_rules] is a map of all invalid transitions as defined by
-    [page_rules] *)
-let rec get_invalid_transitions_aux acc page_rules : unit StringMap.t =
-  match page_rules with
-  | [] -> acc
-  | h :: t ->
-      get_invalid_transitions_aux
-        (acc |> StringMap.add (inverse_page_rule h) ())
-        t
-
-let get_invalid_transitions page_rules =
-  get_invalid_transitions_aux StringMap.empty page_rules
-
-(** [solve page_rules updates] is the solution for this puzzle, given the
-    [page_rules] and a list of [updates].
-
-    BELOW DOESN'T WORK: no guarantee that second page comes immediately after
-    the first
-    - pass in updates to solve
-    - make sliding window of 2 elements
-    - invert element order and concat
-    - check if key is in map from [parse page_rules],
-    - if yes, then it is an illegal transition
-    - if no, then add the list to a list for further processing *)
-let solve page_rules _ =
-  let invalid_transitions = get_invalid_transitions page_rules in
-  ()
-
-let _ =
-  solve
-    [
-      "47|53";
-      "97|13";
-      "97|61";
-      "97|47";
-      "75|29";
-      "61|13";
-      "75|53";
-      "29|13";
-      "97|29";
-      "53|29";
-      "61|53";
-      "97|53";
-      "61|29";
-      "47|13";
-      "75|47";
-      "97|75";
-      "47|61";
-      "75|61";
-      "47|29";
-      "75|13";
-      "53|13";
-    ]
-    []
diff --git a/2024/ocaml/lib/dune b/2024/ocaml/lib/dune
deleted file mode 100644
index 84e62ca..0000000
--- a/2024/ocaml/lib/dune
+++ /dev/null
@@ -1,5 +0,0 @@
-(library
- (name AoC_2024)
- (libraries re2))
-
-(include_subdirs qualified)
diff --git a/2024/ocaml/lib/file/read_input.ml b/2024/ocaml/lib/file/read_input.ml
deleted file mode 100644
index 0f7470b..0000000
--- a/2024/ocaml/lib/file/read_input.ml
+++ /dev/null
@@ -1,11 +0,0 @@
-let rec lines_from_channel ic =
-  try
-    let line = input_line ic in
-    line :: lines_from_channel ic
-  with End_of_file -> []
-
-let lines_from_file filename =
-  let channel = open_in filename in
-  let lines = lines_from_channel channel in
-  close_in channel;
-  lines
diff --git a/2024/ocaml/lib/grid/cell.ml b/2024/ocaml/lib/grid/cell.ml
deleted file mode 100644
index 186e451..0000000
--- a/2024/ocaml/lib/grid/cell.ml
+++ /dev/null
@@ -1,18 +0,0 @@
-type t = {
-  value : string;
-  up : t option;
-  down : t option;
-  left : t option;
-  right : t option;
-}
-
-let create value = { value; up = None; down = None; left = None; right = None }
-let with_up up c = { c with up = Some up }
-let with_down down c = { c with down = Some down }
-let with_left left c = { c with left = Some left }
-let with_right right c = { c with right = Some right }
-let move_up co = match co with Some c -> c.up | None -> None
-let move_down co = match co with Some c -> c.down | None -> None
-let move_left co = match co with Some c -> c.left | None -> None
-let move_right co = match co with Some c -> c.right | None -> None
-let ( = ) c1 c2 = c1.value = c2.value
diff --git a/2024/ocaml/lib/grid/cell.mli b/2024/ocaml/lib/grid/cell.mli
deleted file mode 100644
index e61e34a..0000000
--- a/2024/ocaml/lib/grid/cell.mli
+++ /dev/null
@@ -1,18 +0,0 @@
-type t = {
-  value : string;
-  up : t option;
-  down : t option;
-  left : t option;
-  right : t option;
-}
-
-val create : string -> t
-val with_up : t -> t -> t
-val with_down : t -> t -> t
-val with_left : t -> t -> t
-val with_right : t -> t -> t
-val move_up : t option -> t option
-val move_down : t option -> t option
-val move_left : t option -> t option
-val move_right : t option -> t option
-val ( = ) : t -> t -> bool
diff --git a/2024/ocaml/lib/grid/grid.ml b/2024/ocaml/lib/grid/grid.ml
deleted file mode 100644
index 0d6bc4c..0000000
--- a/2024/ocaml/lib/grid/grid.ml
+++ /dev/null
@@ -1,14 +0,0 @@
-let rec to_grid_aux tokens max_width acc =
-  match tokens with
-  | [] -> acc
-  | h :: t ->
-      let new_cell = Cell.create h |> Cell.with_left acc in
-      let new_acc = acc |> Cell.with_right new_cell in
-      to_grid_aux t max_width new_acc
-
-let to_grid tokens max_width : Cell.t option =
-  match tokens with
-  | [] -> None
-  | h :: t ->
-      let first_cell = Cell.create h in
-      Some (to_grid_aux t max_width first_cell)
diff --git a/2024/ocaml/lib/grid/grid.mli b/2024/ocaml/lib/grid/grid.mli
deleted file mode 100644
index a69fcfe..0000000
--- a/2024/ocaml/lib/grid/grid.mli
+++ /dev/null
@@ -1,6 +0,0 @@
-val to_grid : string list -> int -> Cell.t option
-(** The cell in the top left corner of the grid is returned where each element
-    of [tokens] is converted into rows with [width]. An empty list of [tokens]
-    returns None. Requires: [width] is greater than 0 **)
-
-(* val print : Cell.t -> () *)
diff --git a/2024/ocaml/test/day_01_part_01.ml b/2024/ocaml/test/day_01_part_01.ml
deleted file mode 100644
index 824c95b..0000000
--- a/2024/ocaml/test/day_01_part_01.ml
+++ /dev/null
@@ -1,27 +0,0 @@
-open OUnit2
-open AoC_2024.Day_01.Part_01
-
-let tests =
-  "test suite for day 01 part 01"
-  >::: [
-         ("empty list is 0" >:: fun _ -> assert_equal 0 (solve [] []));
-         ( "distance between 0 and 1 is 1" >:: fun _ ->
-           assert_equal 1 (solve [ 0 ] [ 1 ]) );
-         ( "distance between 1 and 0 is 1" >:: fun _ ->
-           assert_equal 1 (solve [ 1 ] [ 0 ]) );
-         ( "smallest are paired, then next smallest, ..." >:: fun _ ->
-           assert_equal 0 (solve [ 1; 2; 3 ] [ 3; 2; 1 ]) );
-         (* See https://adventofcode.com/2024/day/1 *)
-         ( "solves example correctly" >:: fun _ ->
-           assert_equal 11 (solve [ 3; 4; 2; 1; 3; 3 ] [ 4; 3; 5; 3; 9; 3 ]) );
-         ( "same number is 0 distance apart" >:: fun _ ->
-           assert_equal 0 (calculate_distance 0 0) );
-         ( "same number is 0 distance apart" >:: fun _ ->
-           assert_equal 0 (calculate_distance 1 1) );
-         ( "distance is equal to abs(x - y)" >:: fun _ ->
-           assert_equal 1 (calculate_distance 0 1) );
-         ( "order of inputs doesn't matter" >:: fun _ ->
-           assert_equal 1 (calculate_distance 1 0) );
-       ]
-
-let _ = run_test_tt_main tests
diff --git a/2024/ocaml/test/day_01_part_02.ml b/2024/ocaml/test/day_01_part_02.ml
deleted file mode 100644
index f7340df..0000000
--- a/2024/ocaml/test/day_01_part_02.ml
+++ /dev/null
@@ -1,17 +0,0 @@
-open OUnit2
-open AoC_2024.Day_01.Part_02
-
-let test_solve =
-  "test suite for day 01 part 02"
-  >::: [
-         ("empty list is 0" >:: fun _ -> assert_equal 0 (solve [] []));
-         ( "ten x zero occurrances of ten" >:: fun _ ->
-           assert_equal 0 (solve [ 10 ] [ 1; 2; 3 ]) );
-         ( "two x three occurrances of two" >:: fun _ ->
-           assert_equal 6 (solve [ 2 ] [ 2; 2; 2 ]) );
-         (* See https://adventofcode.com/2024/day/1#part2 *)
-         ( "solves example correctly" >:: fun _ ->
-           assert_equal 31 (solve [ 3; 4; 2; 1; 3; 3 ] [ 4; 3; 5; 3; 9; 3 ]) );
-       ]
-
-let _ = run_test_tt_main test_solve
diff --git a/2024/ocaml/test/day_02_part_01.ml b/2024/ocaml/test/day_02_part_01.ml
deleted file mode 100644
index 36af248..0000000
--- a/2024/ocaml/test/day_02_part_01.ml
+++ /dev/null
@@ -1,38 +0,0 @@
-open OUnit2
-open AoC_2024.Day_02.Part_01
-
-let tests =
-  "test suite for day 2 part 1"
-  >::: [
-         ( "empty list should have no valid reports" >:: fun _ ->
-           assert_equal 0 (solve []) );
-         ( "valid report should count as one" >:: fun _ ->
-           assert_equal 1 (solve [ [ 7; 6; 4; 2; 1 ] ]) );
-         ( "example correct" >:: fun _ ->
-           assert_equal 2
-             (solve
-                [
-                  [ 7; 6; 4; 2; 1 ];
-                  [ 1; 2; 7; 8; 9 ];
-                  [ 9; 7; 6; 2; 1 ];
-                  [ 1; 3; 2; 4; 5 ];
-                  [ 8; 6; 4; 4; 1 ];
-                  [ 1; 3; 6; 7; 9 ];
-                ]) );
-         ( "all increasing" >:: fun _ ->
-           assert_equal true (check_report_safety [ 1; 2; 3 ]) );
-         ( "all decreasing" >:: fun _ ->
-           assert_equal true (check_report_safety [ 3; 2; 1 ]) );
-         ( "increasing and decreasing" >:: fun _ ->
-           assert_equal false (check_report_safety [ 1; 3; 2 ]) );
-         ( "change of at least one" >:: fun _ ->
-           assert_equal true (check_report_safety [ 1; 2; 3 ]) );
-         ( "no change" >:: fun _ ->
-           assert_equal false (check_report_safety [ 1; 1; 2 ]) );
-         ( "change of at most three" >:: fun _ ->
-           assert_equal true (check_report_safety [ 1; 2; 4; 7 ]) );
-         ( "change of at more than three" >:: fun _ ->
-           assert_equal false (check_report_safety [ 1; 5 ]) );
-       ]
-
-let _ = run_test_tt_main tests
diff --git a/2024/ocaml/test/day_03_part_01.ml b/2024/ocaml/test/day_03_part_01.ml
deleted file mode 100644
index 0db039a..0000000
--- a/2024/ocaml/test/day_03_part_01.ml
+++ /dev/null
@@ -1,29 +0,0 @@
-open OUnit2
-open AoC_2024.Day_03.Part_01
-
-let example_input =
-  "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))"
-
-let test_find_mul _ =
-  assert_equal
-    [ "mul(2,4)"; "mul(5,5)"; "mul(11,8)"; "mul(8,5)" ]
-    (let result = find_mul example_input in
-     List.map (fun x -> Re2.Match.get_exn x ~sub:(`Index 0)) result)
-
-let test_extract_pairs _ =
-  assert_equal
-    [ (2, 4); (5, 5); (11, 8); (8, 5) ]
-    (let matches = find_mul example_input in
-     extract_pairs matches)
-
-let test_solve _ = assert_equal ~printer:string_of_int 161 (solve example_input)
-
-let tests =
-  "test suite for day 3 part 1"
-  >::: [
-         "muls extracted from example correctly" >:: test_find_mul;
-         "pairs extracted from matches" >:: test_extract_pairs;
-         "example correctly solved" >:: test_solve;
-       ]
-
-let _ = run_test_tt_main tests
diff --git a/2024/ocaml/test/day_04_part_01.ml b/2024/ocaml/test/day_04_part_01.ml
deleted file mode 100644
index 9550e5b..0000000
--- a/2024/ocaml/test/day_04_part_01.ml
+++ /dev/null
@@ -1,151 +0,0 @@
-open OUnit2
-open AoC_2024.Day_04.Part_01
-
-let example_input =
-  [
-    "MMMSXXMASM";
-    "MSAMXMSMSA";
-    "AMXSXMAAMM";
-    "MSAMASMSMX";
-    "XMASAMXAMM";
-    "XXAMMXXAMA";
-    "SMSMSASXSS";
-    "SAXAMASAAA";
-    "MAMMMXMMMM";
-    "MXMXAXMASX";
-  ]
-
-let is_in_bounds_tests =
-  let test_is_in_bounds expected length index _ =
-    let actual = is_in_bounds length index in
-    assert_equal ~printer:string_of_bool expected actual
-  in
-  [
-    "not in bounds if below 0" >:: test_is_in_bounds false 1 (-1);
-    "in bounds if gte 0 and lt length" >:: test_is_in_bounds true 1 0;
-    "not in bounds if eq length" >:: test_is_in_bounds false 1 1;
-    "not in bounds if gt length" >:: test_is_in_bounds false 1 2;
-  ]
-
-let calculate_num_of_matches_tests =
-  let test_calculate_num_of_matches expected line row_offset character _ =
-    let actual = calculate_num_of_matches line row_offset character in
-    assert_equal ~printer:string_of_int expected actual
-  in
-  [
-    "is 0 when no matches present"
-    >:: test_calculate_num_of_matches 0 "SMMX" 1 { index = 3; character = 'X' };
-    "is 1 when only one match present - top to bottom"
-    >::
-    (*
-      |.|X|.|
-      |.|M|.|
-      |.|A|.|
-      |.|S|.|
-    *)
-    test_calculate_num_of_matches 1 ".X..M..A..S." 3
-      { index = 1; character = 'X' };
-    "is 1 when only one match present - top to bottom edge"
-    >::
-    (*
-      |X|.|.|
-      |M|.|.|
-      |A|.|.|
-      |S|.|.|
-    *)
-    test_calculate_num_of_matches 1 "X..M..A..S.." 3
-      { index = 0; character = 'X' };
-    "is 1 when only one match present - bottom to top"
-    >::
-    (*
-      |.|S|.|
-      |.|A|.|
-      |.|M|.|
-      |.|X|.|
-    *)
-    test_calculate_num_of_matches 1 ".S..A..M..X." 3
-      { index = 10; character = 'X' };
-    "is 1 when only one match present - left to right"
-    >::
-    (*
-      |X|M|A|S|
-    *)
-    test_calculate_num_of_matches 1 "XMAS" 4 { index = 0; character = 'X' };
-    "is 1 when only one match present - right to left"
-    >::
-    (*
-      |S|A|M|X|
-    *)
-    test_calculate_num_of_matches 1 "SAMX" 4 { index = 3; character = 'X' };
-    "is 1 when only one match present - bottom right to top left"
-    >::
-    (*
-      |S|.|.|.|
-      |.|A|.|.|
-      |.|.|M|.|
-      |.|.|.|X|
-    *)
-    test_calculate_num_of_matches 1 "S....A....M....X" 4
-      { index = 15; character = 'X' };
-    "is 1 when only one match present - top left to bottom right"
-    >::
-    (*
-      |X|.|.|.|
-      |.|M|.|.|
-      |.|.|A|.|
-      |.|.|.|S|
-    *)
-    test_calculate_num_of_matches 1 "X....M....A....S" 4
-      { index = 0; character = 'X' };
-    "is 1 when only one match present - bottom left to top right"
-    >::
-    (*
-      |.|.|.|S|
-      |.|.|A|.|
-      |.|M|.|.|
-      |X|.|.|.|
-    *)
-    test_calculate_num_of_matches 1 "...S..A..M..X..." 4
-      { index = 12; character = 'X' };
-    "is 1 when only one match present - top right to bottom left"
-    >::
-    (*
-      |.|.|.|X|
-      |.|.|M|.|
-      |.|A|.|.|
-      |S|.|.|.|
-    *)
-    test_calculate_num_of_matches 1 "...X..M..A..S..." 4
-      { index = 3; character = 'X' };
-    "is 8 when matches present in all possible directions"
-    >::
-    (*
-            |S|.|.|S|.|.|S|
-            |.|A|.|A|.|A|.|
-            |.|.|M|M|M|.|.|
-            |S|A|M|X|M|A|S|
-            |.|.|M|M|M|.|.|
-            |.|A|.|A|.|A|.|
-            |S|.|.|S|.|.|S|
-    *)
-    test_calculate_num_of_matches 8
-      "S..S..S.A.A.A...MMM..SAMXMAS..MMM...A.A.A.S..S..S" 7
-      { index = 24; character = 'X' };
-  ]
-
-let solve_tests =
-  let test_solve expected lines _ =
-    let actual = solve lines in
-    assert_equal ~printer:string_of_int expected actual
-  in
-  [
-    "example is solved correctly" >:: test_solve 18 example_input;
-    "minimal example is solved correctly"
-    >:: test_solve 4 [ "..X..."; ".SAMX."; ".A..A."; "XMAS.S"; ".X...." ];
-  ]
-
-let tests =
-  "test suite for day 4 part 1"
-  >::: is_in_bounds_tests @ calculate_num_of_matches_tests @ solve_tests
-
-let _ = run_test_tt_main tests
diff --git a/2024/ocaml/test/day_05_part_01.ml b/2024/ocaml/test/day_05_part_01.ml
deleted file mode 100644
index 0f50476..0000000
--- a/2024/ocaml/test/day_05_part_01.ml
+++ /dev/null
@@ -1,4 +0,0 @@
-open OUnit2
-
-let tests = "test suite for day n part 1" >::: []
-let _ = run_test_tt_main tests
diff --git a/2024/ocaml/test/dune b/2024/ocaml/test/dune
deleted file mode 100644
index e19cbe9..0000000
--- a/2024/ocaml/test/dune
+++ /dev/null
@@ -1,10 +0,0 @@
-(tests
- (names
-  day_01_part_01
-  day_01_part_02
-  day_02_part_01
-  day_03_part_01
-  day_04_part_01
-  grid)
- (modes byte exe)
- (libraries AoC_2024 ounit2))
diff --git a/2024/ocaml/test/grid.ml b/2024/ocaml/test/grid.ml
deleted file mode 100644
index bd384cd..0000000
--- a/2024/ocaml/test/grid.ml
+++ /dev/null
@@ -1,5 +0,0 @@
-open OUnit2
-open AoC_2024.Grid
-
-let tests = "" >::: []
-let _ = run_test_tt_main tests
diff --git a/ocaml/README.md b/ocaml/README.md
index 7d64eb8..a2a6b4f 100644
--- a/ocaml/README.md
+++ b/ocaml/README.md
@@ -1 +1,21 @@
 # Advent of Code: OCaml
+
+## Getting Started
+
+### How to Build
+
+```sh
+task build
+```
+
+### How to Run
+
+```sh
+task run
+```
+
+### How to Test
+
+```sh
+task test
+```
diff --git a/ocaml/flake.nix b/ocaml/flake.nix
index 0176014..7b267a1 100644
--- a/ocaml/flake.nix
+++ b/ocaml/flake.nix
@@ -39,6 +39,7 @@
             cmdliner # command line library
             ppx_deriving # derivers
             logs # logging library
+            menhir # parsing library
           ];
           sysTools = with pkgs; [
             go-task
@@ -48,4 +49,4 @@
           buildInputs = ocamlPackages ++ sysTools;
         };
     };
-}
+}
\ No newline at end of file
diff --git a/ocaml/lib/year2024/day01/part01.ml b/ocaml/lib/year2024/day01/part01.ml
new file mode 100644
index 0000000..100b12a
--- /dev/null
+++ b/ocaml/lib/year2024/day01/part01.ml
@@ -0,0 +1,40 @@
+(* Day 1: Part 1 *)
+
+let calculate_distance x y = Stdlib.abs (x - y)
+
+(** Require: left and right to be the same length *)
+let solve left right =
+  let sorted_left = List.sort Stdlib.compare left in
+  let sorted_right = List.sort Stdlib.compare right in
+  let distances = List.map2 calculate_distance sorted_left sorted_right in
+  List.fold_left ( + ) 0 distances
+
+let left line =
+  let pos = 0 in
+  let len = String.index line ' ' in
+  String.sub line pos len
+
+let right line =
+  let pos = String.rindex line ' ' + 1 in
+  let len = String.length line - pos in
+  String.sub line pos len
+
+let line_to_tuple line = (left line, right line)
+
+let lines_to_lists lines =
+  let tuples = List.map line_to_tuple lines in
+  let left =
+    List.map
+      (fun t ->
+        let l, _ = t in
+        int_of_string l)
+      tuples
+  in
+  let right =
+    List.map
+      (fun t ->
+        let _, r = t in
+        int_of_string r)
+      tuples
+  in
+  (left, right)
diff --git a/ocaml/lib/year2024/day01/part02.ml b/ocaml/lib/year2024/day01/part02.ml
new file mode 100644
index 0000000..25c8b7d
--- /dev/null
+++ b/ocaml/lib/year2024/day01/part02.ml
@@ -0,0 +1,44 @@
+(* Day 1: Part 2 *)
+
+let rec count_occurrances_help element acc lst =
+  match lst with
+  | [] -> acc
+  | h :: t ->
+      if h = element then count_occurrances_help element (acc + 1) t
+      else count_occurrances_help element acc t
+
+let count_occurrances element lst = count_occurrances_help element 0 lst
+
+let solve left right =
+  List.map (fun x -> x * count_occurrances x right) left
+  |> List.fold_left ( + ) 0
+
+let left line =
+  let pos = 0 in
+  let len = String.index line ' ' in
+  String.sub line pos len
+
+let right line =
+  let pos = String.rindex line ' ' + 1 in
+  let len = String.length line - pos in
+  String.sub line pos len
+
+let line_to_tuple line = (left line, right line)
+
+let lines_to_lists lines =
+  let tuples = List.map line_to_tuple lines in
+  let left =
+    List.map
+      (fun t ->
+        let l, _ = t in
+        int_of_string l)
+      tuples
+  in
+  let right =
+    List.map
+      (fun t ->
+        let _, r = t in
+        int_of_string r)
+      tuples
+  in
+  (left, right)
diff --git a/ocaml/lib/year2024/day02/part01.ml b/ocaml/lib/year2024/day02/part01.ml
new file mode 100644
index 0000000..32d7ab8
--- /dev/null
+++ b/ocaml/lib/year2024/day02/part01.ml
@@ -0,0 +1,42 @@
+(* Day 2: Part 1 *)
+
+type level = int
+type reports = level list list
+
+let rec compare_report_levels_helper comparison prev report =
+  match report with
+  | [] -> true
+  | h :: t -> comparison prev h && compare_report_levels_helper comparison h t
+
+let compare_report_levels comparison report =
+  match report with
+  | [] -> true
+  | h :: t -> compare_report_levels_helper comparison h t
+
+let all_increasing report = compare_report_levels ( < ) report
+let all_decreasing report = compare_report_levels ( > ) report
+
+let at_least_one report =
+  compare_report_levels (fun prev curr -> prev <> curr) report
+
+let at_most_three report =
+  compare_report_levels (fun prev curr -> abs (prev - curr) <= 3) report
+
+let check_report_safety report =
+  if not (all_increasing report || all_decreasing report) then false
+  else if not (at_least_one report && at_most_three report) then false
+  else true
+
+let rec count_safe_reports acc lst =
+  match lst with
+  | [] -> acc
+  | h :: t ->
+      if h then count_safe_reports (acc + 1) t else count_safe_reports acc t
+
+let solve reports =
+  reports |> List.map check_report_safety |> count_safe_reports 0
+
+let line_to_report line =
+  line |> String.split_on_char ' ' |> List.map int_of_string
+
+let lines_to_reports lines = List.map line_to_report lines
diff --git a/ocaml/lib/year2024/day03/part01.ml b/ocaml/lib/year2024/day03/part01.ml
new file mode 100644
index 0000000..c12b68a
--- /dev/null
+++ b/ocaml/lib/year2024/day03/part01.ml
@@ -0,0 +1,33 @@
+(* Day 3: Part 1 *)
+
+let find_mul text =
+  let regex_or_err = Re2.create "mul\\(([0-9]{1,3}),([0-9]{1,3})\\)" in
+  match regex_or_err with
+  | Ok regex -> (
+      let matches = Re2.get_matches regex text in
+      match matches with Ok matches -> matches | Error _ -> [])
+  | Error _ -> []
+
+let extract_pairs (matches : Re2.Match.t list) : (int * int) list =
+  List.map
+    (fun x ->
+      let left = Re2.Match.get x ~sub:(`Index 1) in
+      match left with
+      | None -> (0, 0)
+      | Some left -> (
+          let left_num = int_of_string left in
+          let right = Re2.Match.get x ~sub:(`Index 2) in
+          match right with
+          | None -> (0, 0)
+          | Some right ->
+              let right_num = int_of_string right in
+              (left_num, right_num)))
+    matches
+
+let solve input =
+  input |> find_mul |> extract_pairs
+  |> List.fold_left
+       (fun acc pair ->
+         let left, right = pair in
+         acc + (left * right))
+       0
diff --git a/ocaml/lib/year2024/day04/part01.ml b/ocaml/lib/year2024/day04/part01.ml
new file mode 100644
index 0000000..acb3e3b
--- /dev/null
+++ b/ocaml/lib/year2024/day04/part01.ml
@@ -0,0 +1,85 @@
+(* Day 4: Part 1 *)
+
+type character = { index : int; character : char }
+type direction = N | NE | E | SE | S | SW | W | NW
+
+let all_directions = [ N; NE; E; SE; S; SW; W; NW ]
+let needle = "XMAS"
+
+(** [calculate_row_offset lines] is the offset used to move between the rows of
+    the concatenated variant of [lines] as though it were a grid. Requires:
+    values of [lines] all have the same length *)
+let calculate_row_offset lines =
+  match lines with [] -> 0 | h :: _ -> String.length h
+
+let join_lines lines =
+  let concat_trim acc line = acc ^ String.trim line in
+  List.fold_left concat_trim "" lines
+
+let explode s = List.init (String.length s) (String.get s)
+let is_in_bounds length index = index >= 0 && index < length
+
+let get_at_index line index =
+  let length = String.length line in
+  if not (is_in_bounds length index) then "."
+  else
+    let character = String.get line index in
+    Char.escaped character
+
+let get_direction_index row_offset direction index =
+  match direction with
+  | N -> index - row_offset
+  | NE -> index - row_offset + 1
+  | E -> index + 1
+  | SE -> index + row_offset + 1
+  | S -> index + row_offset
+  | SW -> index + row_offset - 1
+  | W -> index - 1
+  | NW -> index - row_offset - 1
+
+let get_direction_string get_char get_offset_index index =
+  let first = get_char index in
+  let second_index = get_offset_index index in
+  let second = get_char second_index in
+  let third_index = get_offset_index second_index in
+  let third = get_char third_index in
+  let fourth_index = get_offset_index third_index in
+  let fourth = get_char fourth_index in
+  first ^ second ^ third ^ fourth
+
+let check_direction get_from_line get_offset_index index direction =
+  get_direction_string get_from_line (get_offset_index direction) index = needle
+
+let calculate_num_of_matches line row_offset character =
+  let get_from_line_at_index = get_at_index line in
+  let get_offset_direction_index = get_direction_index row_offset in
+  let check_direction_from_index =
+    check_direction get_from_line_at_index get_offset_direction_index
+      character.index
+  in
+  all_directions
+  |> List.map check_direction_from_index
+  |> List.map (fun x -> match x with true -> 1 | false -> 0)
+  |> List.fold_left ( + ) 0
+
+(* Tried:
+   2544 -> too high
+   1272 (previous halved) -> too low *)
+let solve lines =
+  let row_offset = calculate_row_offset lines in
+  let line = join_lines lines in
+  let chars = explode line in
+  let characters = List.mapi (fun i c -> { index = i; character = c }) chars in
+  let xs =
+    List.filter
+      (fun c -> match c.character with 'X' -> true | _ -> false)
+      characters
+  in
+  let calculate_num_of_surrounding_matches_in_line =
+    calculate_num_of_matches line row_offset
+  in
+  let num_of_matches =
+    List.map calculate_num_of_surrounding_matches_in_line xs
+    |> List.fold_left ( + ) 0
+  in
+  num_of_matches
diff --git a/ocaml/lib/year2024/day05/part01.ml b/ocaml/lib/year2024/day05/part01.ml
new file mode 100644
index 0000000..96ff486
--- /dev/null
+++ b/ocaml/lib/year2024/day05/part01.ml
@@ -0,0 +1,64 @@
+(* Day 5: Part 1 *)
+
+module StringMap = Map.Make (String)
+
+let inverse_page_rule page_rule =
+  String.split_on_char '|' page_rule
+  |> fun lst ->
+  match lst with [] -> "" | _ :: _ -> String.concat "|" (List.rev lst)
+
+(** [parse_aux acc page_rules] is a map of all invalid transitions as defined by
+    [page_rules] *)
+let rec get_invalid_transitions_aux acc page_rules : unit StringMap.t =
+  match page_rules with
+  | [] ->
+      acc
+  | h :: t ->
+      get_invalid_transitions_aux
+        (acc |> StringMap.add (inverse_page_rule h) ())
+        t
+
+let get_invalid_transitions page_rules =
+  get_invalid_transitions_aux StringMap.empty page_rules
+
+(** [solve page_rules updates] is the solution for this puzzle, given the
+    [page_rules] and a list of [updates].
+
+    BELOW DOESN'T WORK: no guarantee that second page comes immediately after
+    the first
+    - pass in updates to solve
+    - make sliding window of 2 elements
+    - invert element order and concat
+    - check if key is in map from [parse page_rules],
+    - if yes, then it is an illegal transition
+    - if no, then add the list to a list for further processing *)
+let solve page_rules _ =
+  let[@warning "-26"] invalid_transitions =
+    get_invalid_transitions page_rules
+  in
+  ()
+
+let _ =
+  solve
+    [ "47|53"
+    ; "97|13"
+    ; "97|61"
+    ; "97|47"
+    ; "75|29"
+    ; "61|13"
+    ; "75|53"
+    ; "29|13"
+    ; "97|29"
+    ; "53|29"
+    ; "61|53"
+    ; "97|53"
+    ; "61|29"
+    ; "47|13"
+    ; "75|47"
+    ; "97|75"
+    ; "47|61"
+    ; "75|61"
+    ; "47|29"
+    ; "75|13"
+    ; "53|13" ]
+    []
diff --git a/ocaml/lib/year2024/dune b/ocaml/lib/year2024/dune
new file mode 100644
index 0000000..63bf2a1
--- /dev/null
+++ b/ocaml/lib/year2024/dune
@@ -0,0 +1,5 @@
+(include_subdirs qualified)
+
+(library
+ (name year2024)
+ (libraries re2))
diff --git a/ocaml/test/year2024/day01/dune b/ocaml/test/year2024/day01/dune
new file mode 100644
index 0000000..8891ccf
--- /dev/null
+++ b/ocaml/test/year2024/day01/dune
@@ -0,0 +1,11 @@
+(tests
+ (names
+   test_part01
+   test_part02)
+ (libraries
+   year2024
+   alcotest
+   qcheck-core
+   qcheck-alcotest)
+ (action (run %{test} -e))
+ (modes byte exe))
diff --git a/ocaml/test/year2024/day01/test_part01.ml b/ocaml/test/year2024/day01/test_part01.ml
new file mode 100644
index 0000000..706284d
--- /dev/null
+++ b/ocaml/test/year2024/day01/test_part01.ml
@@ -0,0 +1,30 @@
+open Year2024.Day01.Part01
+
+let test_solve haveLeft haveRight want () =
+  Alcotest.(check int) "incorrect solution" want @@ solve haveLeft haveRight
+
+let test_distance_calculation haveX haveY want () =
+  Alcotest.(check int) "incorrect solution" want
+  @@ calculate_distance haveX haveY
+
+let () =
+  let open Alcotest in
+  run "test suite for day 01 part 01"
+    [ ( "test solutions"
+      , [ test_case "empty list is 0" `Quick @@ (test_solve [] []) 0
+        ; test_case "distance between 0 and 1 is 1" `Quick
+          @@ (test_solve [0] [1]) 1
+        ; test_case "distance between 1 and 0 is 1" `Quick
+          @@ (test_solve [1] [0]) 1
+        ; test_case "smallest are paired, then next smallest, ..." `Quick
+          @@ (test_solve [1; 2; 3] [3; 2; 1]) 0
+        ; test_case "solves example correctly" `Quick
+          @@ (test_solve [3; 4; 2; 1; 3; 3] [4; 3; 5; 3; 9; 3]) 11
+        ; test_case "same number is 0 distance apart" `Quick
+          @@ (test_distance_calculation 0 0) 0
+        ; test_case "same number is 0 distance apart" `Quick
+          @@ (test_distance_calculation 1 1) 0
+        ; test_case "distance is equal to abs(x - y)" `Quick
+          @@ (test_distance_calculation 0 1) 1
+        ; test_case "order of inputs doesn't matter" `Quick
+          @@ (test_distance_calculation 1 0) 1 ] ) ]
diff --git a/ocaml/test/year2024/day01/test_part02.ml b/ocaml/test/year2024/day01/test_part02.ml
new file mode 100644
index 0000000..142add6
--- /dev/null
+++ b/ocaml/test/year2024/day01/test_part02.ml
@@ -0,0 +1,16 @@
+open Year2024.Day01.Part02
+
+let test_solve haveLeft haveRight want () =
+  Alcotest.(check int) "incorrect solution" want @@ solve haveLeft haveRight
+
+let () =
+  let open Alcotest in
+  run "test suite for day 01 part 02"
+    [ ( "test solutions"
+      , [ test_case "empty list is 0" `Quick @@ (test_solve [] []) 0
+        ; test_case "ten x zero occurrances of ten" `Quick
+          @@ (test_solve [10] [1; 2; 3]) 0
+        ; test_case "two x three occurrances of two" `Quick
+          @@ (test_solve [2] [2; 2; 2]) 6
+        ; test_case "solves example correctly" `Quick
+          @@ (test_solve [3; 4; 2; 1; 3; 3] [4; 3; 5; 3; 9; 3]) 31 ] ) ]
diff --git a/ocaml/test/year2024/day02/dune b/ocaml/test/year2024/day02/dune
new file mode 100644
index 0000000..c4a75c4
--- /dev/null
+++ b/ocaml/test/year2024/day02/dune
@@ -0,0 +1,10 @@
+(tests
+ (names
+   test_part01)
+ (libraries
+   year2024
+   alcotest
+   qcheck-core
+   qcheck-alcotest)
+ (action (run %{test} -e))
+ (modes byte exe))
diff --git a/ocaml/test/year2024/day02/test_part01.ml b/ocaml/test/year2024/day02/test_part01.ml
new file mode 100644
index 0000000..4feea41
--- /dev/null
+++ b/ocaml/test/year2024/day02/test_part01.ml
@@ -0,0 +1,41 @@
+open Year2024.Day02.Part01
+
+let test_solve have want () =
+  Alcotest.(check int) "incorrect solution" want @@ solve have
+
+let test_report_safety_check have want () =
+  Alcotest.(check bool) "incorrect report safety" want
+  @@ check_report_safety have
+
+let () =
+  let open Alcotest in
+  run "test suite for day 2 part 1"
+    [ ( "test solutions"
+      , [ test_case "empty list should have no valid reports" `Quick
+          @@ test_solve [] 0
+        ; test_case "valid report should count as one" `Quick
+          @@ test_solve [[7; 6; 4; 2; 1]] 1
+        ; test_case "provided example" `Quick
+          @@ test_solve
+               [ [7; 6; 4; 2; 1]
+               ; [1; 2; 7; 8; 9]
+               ; [9; 7; 6; 2; 1]
+               ; [1; 3; 2; 4; 5]
+               ; [8; 6; 4; 4; 1]
+               ; [1; 3; 6; 7; 9] ]
+               2 ] )
+    ; ( "test report safety check"
+      , [ test_case "all increasing" `Quick
+          @@ test_report_safety_check [1; 2; 3] true
+        ; test_case "all decreasing" `Quick
+          @@ test_report_safety_check [3; 2; 1] true
+        ; test_case "increasing and decreasing" `Quick
+          @@ test_report_safety_check [1; 3; 2] false
+        ; test_case "change of at least one" `Quick
+          @@ test_report_safety_check [1; 2; 3] true
+        ; test_case "no change" `Quick
+          @@ test_report_safety_check [1; 1; 2] false
+        ; test_case "change of at most three" `Quick
+          @@ test_report_safety_check [1; 2; 4; 7] true
+        ; test_case "change of at more than three" `Quick
+          @@ test_report_safety_check [1; 5] false ] ) ]
diff --git a/ocaml/test/year2024/day03/dune b/ocaml/test/year2024/day03/dune
new file mode 100644
index 0000000..c4a75c4
--- /dev/null
+++ b/ocaml/test/year2024/day03/dune
@@ -0,0 +1,10 @@
+(tests
+ (names
+   test_part01)
+ (libraries
+   year2024
+   alcotest
+   qcheck-core
+   qcheck-alcotest)
+ (action (run %{test} -e))
+ (modes byte exe))
diff --git a/ocaml/test/year2024/day03/test_part01.ml b/ocaml/test/year2024/day03/test_part01.ml
new file mode 100644
index 0000000..78d04e2
--- /dev/null
+++ b/ocaml/test/year2024/day03/test_part01.ml
@@ -0,0 +1,29 @@
+open Year2024.Day03.Part01
+
+let example_input =
+  "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))"
+
+let test_find_mul () =
+  Alcotest.(check (list string))
+    "incorrect mul list found"
+    ["mul(2,4)"; "mul(5,5)"; "mul(11,8)"; "mul(8,5)"]
+    (let result = find_mul example_input in
+     List.map (fun x -> Re2.Match.get_exn x ~sub:(`Index 0)) result )
+
+let test_extract_pairs () =
+  Alcotest.(check (list (pair int int)))
+    "incorrect pairs"
+    [(2, 4); (5, 5); (11, 8); (8, 5)]
+    (let matches = find_mul example_input in
+     extract_pairs matches )
+
+let test_solve () = Alcotest.(check int) "" 161 @@ solve example_input
+
+let () =
+  let open Alcotest in
+  run "test suite for day 3 part 1"
+    [ ( "test implementation"
+      , [ test_case "muls extracted from example correctly" `Quick
+          @@ test_find_mul
+        ; test_case "pairs extracted from matches" `Quick @@ test_extract_pairs
+        ; test_case "example correctly solved" `Quick @@ test_solve ] ) ]
diff --git a/ocaml/test/year2024/day04/dune b/ocaml/test/year2024/day04/dune
new file mode 100644
index 0000000..c4a75c4
--- /dev/null
+++ b/ocaml/test/year2024/day04/dune
@@ -0,0 +1,10 @@
+(tests
+ (names
+   test_part01)
+ (libraries
+   year2024
+   alcotest
+   qcheck-core
+   qcheck-alcotest)
+ (action (run %{test} -e))
+ (modes byte exe))
diff --git a/ocaml/test/year2024/day04/test_part01.ml b/ocaml/test/year2024/day04/test_part01.ml
new file mode 100644
index 0000000..5776e49
--- /dev/null
+++ b/ocaml/test/year2024/day04/test_part01.ml
@@ -0,0 +1,141 @@
+open Year2024.Day04.Part01
+
+let example_input =
+  [ "MMMSXXMASM"
+  ; "MSAMXMSMSA"
+  ; "AMXSXMAAMM"
+  ; "MSAMASMSMX"
+  ; "XMASAMXAMM"
+  ; "XXAMMXXAMA"
+  ; "SMSMSASXSS"
+  ; "SAXAMASAAA"
+  ; "MAMMMXMMMM"
+  ; "MXMXAXMASX" ]
+
+let is_in_bounds_tests =
+  let test_is_in_bounds expected length index _ =
+    let actual = is_in_bounds length index in
+    assert_equal ~printer:string_of_bool expected actual
+  in
+  [ "not in bounds if below 0" >:: test_is_in_bounds false 1 (-1)
+  ; "in bounds if gte 0 and lt length" >:: test_is_in_bounds true 1 0
+  ; "not in bounds if eq length" >:: test_is_in_bounds false 1 1
+  ; "not in bounds if gt length" >:: test_is_in_bounds false 1 2 ]
+
+let calculate_num_of_matches_tests =
+  let test_calculate_num_of_matches expected line row_offset character _ =
+    let actual = calculate_num_of_matches line row_offset character in
+    assert_equal ~printer:string_of_int expected actual
+  in
+  [ "is 0 when no matches present"
+    >:: test_calculate_num_of_matches 0 "SMMX" 1 {index= 3; character= 'X'}
+  ; "is 1 when only one match present - top to bottom"
+    >::
+    (*
+      |.|X|.|
+      |.|M|.|
+      |.|A|.|
+      |.|S|.|
+    *)
+    test_calculate_num_of_matches 1 ".X..M..A..S." 3 {index= 1; character= 'X'}
+  ; "is 1 when only one match present - top to bottom edge"
+    >::
+    (*
+      |X|.|.|
+      |M|.|.|
+      |A|.|.|
+      |S|.|.|
+    *)
+    test_calculate_num_of_matches 1 "X..M..A..S.." 3 {index= 0; character= 'X'}
+  ; "is 1 when only one match present - bottom to top"
+    >::
+    (*
+      |.|S|.|
+      |.|A|.|
+      |.|M|.|
+      |.|X|.|
+    *)
+    test_calculate_num_of_matches 1 ".S..A..M..X." 3 {index= 10; character= 'X'}
+  ; "is 1 when only one match present - left to right"
+    >::
+    (*
+      |X|M|A|S|
+    *)
+    test_calculate_num_of_matches 1 "XMAS" 4 {index= 0; character= 'X'}
+  ; "is 1 when only one match present - right to left"
+    >::
+    (*
+      |S|A|M|X|
+    *)
+    test_calculate_num_of_matches 1 "SAMX" 4 {index= 3; character= 'X'}
+  ; "is 1 when only one match present - bottom right to top left"
+    >::
+    (*
+      |S|.|.|.|
+      |.|A|.|.|
+      |.|.|M|.|
+      |.|.|.|X|
+    *)
+    test_calculate_num_of_matches 1 "S....A....M....X" 4
+      {index= 15; character= 'X'}
+  ; "is 1 when only one match present - top left to bottom right"
+    >::
+    (*
+      |X|.|.|.|
+      |.|M|.|.|
+      |.|.|A|.|
+      |.|.|.|S|
+    *)
+    test_calculate_num_of_matches 1 "X....M....A....S" 4
+      {index= 0; character= 'X'}
+  ; "is 1 when only one match present - bottom left to top right"
+    >::
+    (*
+      |.|.|.|S|
+      |.|.|A|.|
+      |.|M|.|.|
+      |X|.|.|.|
+    *)
+    test_calculate_num_of_matches 1 "...S..A..M..X..." 4
+      {index= 12; character= 'X'}
+  ; "is 1 when only one match present - top right to bottom left"
+    >::
+    (*
+      |.|.|.|X|
+      |.|.|M|.|
+      |.|A|.|.|
+      |S|.|.|.|
+    *)
+    test_calculate_num_of_matches 1 "...X..M..A..S..." 4
+      {index= 3; character= 'X'}
+  ; "is 8 when matches present in all possible directions"
+    >::
+    (*
+            |S|.|.|S|.|.|S|
+            |.|A|.|A|.|A|.|
+            |.|.|M|M|M|.|.|
+            |S|A|M|X|M|A|S|
+            |.|.|M|M|M|.|.|
+            |.|A|.|A|.|A|.|
+            |S|.|.|S|.|.|S|
+    *)
+    test_calculate_num_of_matches 8
+      "S..S..S.A.A.A...MMM..SAMXMAS..MMM...A.A.A.S..S..S" 7
+      {index= 24; character= 'X'} ]
+
+let solve_tests =
+  let test_solve have want () =
+    let actual = solve have in
+    Alcotest.(check int) "incorrect solution" want actual
+  in
+  [ ( "test solution"
+    , [ Alcotest.test_case "example is solved correctly" `Quick
+        @@ test_solve example_input 18
+      ; Alcotest.test_case "minimal example is solved correctly" `Quick
+        @@ test_solve ["..X..."; ".SAMX."; ".A..A."; "XMAS.S"; ".X...."] 4 ] )
+  ]
+
+let () =
+  let open Alcotest in
+  run "test suite for day 4 part 1" is_in_bounds_tests
+  @ calculate_num_of_matches_tests @ solve_tests
-- 
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