AOC2022 day25

main.dart

// AOC 2022, Day 25: Full of Hot Air
// Convert numbers to "balanced base"(q.v.) 5 and back
// https://dartpad.dev/?id=004680836fce05e69a8be7e05b68cf3c

import 'package:collection/collection.dart';

var si = {'2': 2, '1': 1, '0': 0, '-': -1, '=': -2};
var i2s = ['0', '1', '2', '=', '-'];
int sToI(String n) => n.split('').fold(0, (int s, String t) => s * 5 + si[t]!);
String iToS(int i) => [
      for (var j = i; j > 0; j = (j ~/ 5) + ((j % 5 >= 3) ? 1 : 0)) i2s[j % 5]
    ].reversed.join();

part1(List<String> lines) => iToS(lines.map(sToI).sum);

const testdata = [
  "1=-0-2",
  "12111",
  "2=0=",
  "21",
  "2=01",
  "111",
  "20012",
  "112",
  "1=-1=",
  "1-12",
  "12",
  "1=",
  "122"
];

void main(List<String> args) {
  var dt = DateTime.now();
  assert(part1(testdata) == "2=-1=0");
  var rt = DateTime.now().difference(dt).inMilliseconds;
  print('tests succeeded in $rt ms');
}