adventofcode2025/05/code.js

import { readFileSync } from 'node:fs';

let sampleMode = false;
let usedArray = [];

const sampleArray = readFileSync('sample.txt').toString().split("\n");
const inputArray = readFileSync('input.txt').toString().split("\n");

if (sampleMode) {
  usedArray = sampleArray;
} else {
  usedArray = inputArray;
}

// Part One

console.time("part1");

const ranges = [];
const ingredients = [];
const validIngredients = [];

for (const element of usedArray) {
  if (element.includes("-")) {
    const contents = element.split("-");
    const start = Number.parseInt(contents[0]);
    const end = Number.parseInt(contents[1]);
    ranges.push({ start, end });
  } else if (element !== "") {
    ingredients.push(Number.parseInt(element));
  }
}

for (const ingredient of ingredients) {
  for (const range of ranges) {
    if (ingredient >= range.start && ingredient <= range.end) {
      validIngredients.push(ingredient);
      break;
    }
  }
}

console.timeEnd("part1");
console.log(validIngredients.length);


// Part Two

console.time("part2");

const ranges2 = [];

for (const element of usedArray) {
  if (element.includes("-")) {
    const contents = element.split("-");
    const start = Number.parseInt(contents[0]);
    const end = Number.parseInt(contents[1]);
    ranges2.push({ start, end });
  }
}

ranges2.sort((a, b) => a.start - b.start);
let processing = true;

while (processing) {
  compactRanges();
}

// Five more times for fun, just in case
for (let i = 0; i < 5; i++) {
  compactRanges();
}

let sum = 0;
for (const range of ranges2) {
  sum += range.end - range.start + 1;
}

console.timeEnd("part2");
console.log(sum);

// functions

function compactRanges() {
  let continuing = false;
  let i = 0;
  while (i < ranges2.length - 1) {
    if (ranges2[i + 1].start <= ranges2[i].end + 1) {
      ranges2[i].end = Math.max(ranges2[i].end, ranges2[i + 1].end);
      ranges2.splice(i + 1, 1);
      continuing = true;
    } else {
      i++;
    }
  }
  processing = continuing;
}