{ lib, utils, ... }:
with lib;
with builtins;
with utils;
let
  records = map (l:
    let s = reSplit ": " l;
    in {
      target = toInt (head s);
      candidates = map toInt (splitWhitespace (last s));
    }) (readLines ./input);

  concatInts = x: y: toIntBase10 "${toString x}${toString y}";

  canProduce' = current: target: candidates: ops:
    if current > target then
      false
    else if candidates == [ ] then
      current == target
    else
      any (op:
        canProduce' (op current (head candidates)) target (tail candidates) ops)
      ops;

  canProduce = operators: r:
    if r.candidates == [ ] then
      r.target == 0
    else
      canProduce' (head r.candidates) r.target (tail r.candidates) operators;

in {
  part1 =
    listSumWith (getAttr "target") (filter (canProduce [ add mul ]) records);
  part2 = listSumWith (getAttr "target")
    (filter (canProduce [ add mul concatInts ]) records);
}