aoc25/solutions/02.ts

58 lines
No EOL
1.8 KiB
TypeScript

import { solvables } from "../main.ts";
import type { Solvable } from "../solvable.ts";
import { readInput } from "../utils.ts";
// check if pattern with given width repeats in input
const checkWindow = (width: number, input: number): boolean => {
const str = String(input);
for (let patternStart = 0; patternStart + 2 * width < str.length; patternStart += width) {
const leftPatIdx = [patternStart, patternStart + width]
const rightPatIdx = [patternStart + width, patternStart + width + width]
const patternRepeated = str.slice(...leftPatIdx) === str.slice(...rightPatIdx);
if (patternRepeated) {
return true;
}
}
return false
}
class DayTwo implements Solvable {
input = readInput('02')
public part1(): DayTwo {
const vals: [number, number][] = this.input
.split(",")
.map(range => range.split("-")
.map(Number) as [number, number]);
const invalid: number[] = [];
for (const [start, end] of vals) {
for (let i = start; i <= end; i++) {
// if the number is of odd length, it can't have a repeating pattern
if (String(i).length % 2 !== 0) {
continue;
}
// check for patterns with increasing width but never exceeding half the length of the number
for (let width = 2; width <= String(i).length / 2; width++) {
if (checkWindow(width, i)) {
invalid.push(i);
break;
}
}
}
}
console.log(invalid.reduce((a, b) => a + b, 0))
return this
}
public part2(): DayTwo {
return this
}
}
solvables.push(new DayTwo())