76 lines
No EOL
2.7 KiB
Nix
76 lines
No EOL
2.7 KiB
Nix
let
|
|
# Import nixpkgs lib and input file
|
|
inherit ((builtins.getFlake (builtins.toString ./..)).inputs.nixpkgs) lib;
|
|
input = builtins.readFile (builtins.toString ./input.txt);
|
|
|
|
# Define functions
|
|
matElem = row: col: mat: builtins.elemAt (builtins.elemAt mat row) col;
|
|
matDet = m: ((matElem 0 0 m) * (matElem 1 1 m)) - ((matElem 0 1 m) * (matElem 1 0 m));
|
|
|
|
# Parse input
|
|
split = builtins.map
|
|
(s:
|
|
let
|
|
split = lib.strings.splitString "\n" s;
|
|
in { a = builtins.elemAt split 0; b = builtins.elemAt split 1; prize = builtins.elemAt split 2; }
|
|
)
|
|
(lib.strings.splitString "\n\n" input);
|
|
extracted = builtins.map
|
|
({ a, b, prize }: {
|
|
a = lib.strings.splitString ", Y+" (builtins.substring 12 (-1) a);
|
|
b = lib.strings.splitString ", Y+" (builtins.substring 12 (-1) b);
|
|
prize = lib.strings.splitString ", Y=" (builtins.substring 9 (-1) prize);
|
|
}) split;
|
|
numbered = builtins.map
|
|
({ a, b, prize }: {
|
|
a = { x = lib.strings.toInt (builtins.elemAt a 0); y = lib.strings.toInt (builtins.elemAt a 1); };
|
|
b = { x = lib.strings.toInt (builtins.elemAt b 0); y = lib.strings.toInt (builtins.elemAt b 1); };
|
|
prize = { x = lib.strings.toInt (builtins.elemAt prize 0); y = lib.strings.toInt (builtins.elemAt prize 1); };
|
|
}) extracted;
|
|
|
|
# Solve system of equations
|
|
mathified = builtins.map
|
|
({ a, b, prize }: {
|
|
# First equation
|
|
a1 = a.x;
|
|
b1 = b.x;
|
|
c1 = prize.x;
|
|
# Second equation
|
|
a2 = a.y;
|
|
b2 = b.y;
|
|
c2 = prize.y;
|
|
}) numbered;
|
|
determinants = builtins.map
|
|
({ a1, b1, c1, a2, b2, c2 }: {
|
|
numerators = {
|
|
a = matDet [
|
|
[ c1 b1 ]
|
|
[ c2 b2 ]
|
|
];
|
|
b = matDet [
|
|
[ a1 c1 ]
|
|
[ a2 c2 ]
|
|
];
|
|
};
|
|
denominator = matDet [
|
|
[ a1 b1 ]
|
|
[ a2 b2 ]
|
|
];
|
|
}) mathified;
|
|
tokens = (
|
|
lib.lists.foldr
|
|
({ numerators, denominator }: accumulated-tokens:
|
|
accumulated-tokens + (
|
|
if (
|
|
(lib.trivial.mod numerators.a denominator) != 0
|
|
|| (lib.trivial.mod numerators.b denominator) != 0
|
|
)
|
|
then 0
|
|
else (numerators.a / denominator) * 3 + (numerators.b / denominator)
|
|
)
|
|
)
|
|
0
|
|
) determinants;
|
|
|
|
output = tokens;
|
|
in output |