(*
"Great work; looks like we're on the right track after all. Here's a star for
your effort." However, the program seems a little worried. Can programs be
worried?

"Based on what we're seeing, it looks like all the User wanted is some
information about the evenly divisible values in the spreadsheet.
Unfortunately, none of us are equipped for that kind of calculation - most of
us specialize in bitwise operations."

It sounds like the goal is to find the only two numbers in each row where one
evenly divides the other - that is, where the result of the division operation
is a whole number. They would like you to find those numbers on each line,
divide them, and add up each line's result.

For example, given the following spreadsheet:

5 9 2 8
9 4 7 3
3 8 6 5

    In the first row, the only two numbers that evenly divide are 8 and 2; the result of this division is 4.
    In the second row, the two numbers are 9 and 3; the result is 3.
    In the third row, the result is 2.

In this example, the sum of the results would be 4 + 3 + 2 = 9.

What is the sum of each row's result in your puzzle input?
*)

open Batteries

let rec find_divideable' (rest : int list) (current : int) =
    match rest with
    | [] -> 0
    | hd :: tl ->
            if hd != current && hd mod current == 0
            then hd / current
            else find_divideable' tl current

let find_divideable (lst : int list) =
    List.map (find_divideable' lst) lst

let parse_line line =
    String.split_on_char '\t' line
    |> List.map int_of_string
    |> find_divideable
    |> List.sum

let parse_input input =
    Enum.map parse_line input
    |> Enum.sum

let () =
    "dec2_input"
    |> File.lines_of
    |> parse_input
    |> print_int