day 1 part1

2024/day1/.gitignore

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+*.out
+*.cmi
+*.cmx
+*.o

2024/day1/.ocamlformat

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+profile = janestreet

2024/day1/Makefile

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+CC = ocamlopt
+RM = rm -rf
+
+NAME = main
+EXE  = a.out
+LIB  = unix.cmxa -I +unix
+
+
+all: run
+
+compilation:
+	$(CC) -o $(EXE) $(LIB) $(NAME).ml
+
+run: compilation
+	./$(EXE)
+
+EXTS = cmi cmx o
+clean:
+	$(RM) $(EXE) $(foreach ext,$(EXTS),$(NAME).$(ext))

2024/day1/main.ml

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+(** Get input *)
+let from input =
+  let ic = open_in input in
+  (* Read a file *)
+  let rec read_line acc =
+    try
+      let line = input_line ic in
+      read_line (line :: acc)
+    with
+    | End_of_file ->
+      close_in ic;
+      acc
+  in
+  (* Split column into couples *)
+  let scan line = Scanf.sscanf line "%d %d" (fun x y -> x, y) in
+  (* Split couple into 2 lists *)
+  let split (acc1, acc2) (a, b) = a :: acc1, b :: acc2 in
+  let zip = List.map scan (read_line []) in
+  List.fold_left split ([], []) zip
+;;
+
+let first a b =
+  let sorted_a, sorted_b = List.fast_sort compare a, List.fast_sort compare b in
+  let m = List.map2 (fun a b -> Int.abs (a - b)) sorted_a sorted_b in
+  List.fold_left ( + ) 0 m
+;;
+
+let second a b =
+  (* todo *)
+  0
+;;
+
+let _ =
+  let a, b = from "input.txt" in
+  print_endline ("first: " ^ Int.to_string (first a b));
+  print_endline ("second: " ^ Int.to_string (second a b))
+;;