day09.js

const fs = require('fs').promises;

(async () => {
  console.log(`Reading input from ${__dirname}/${process.argv[2]}.txt`);
  const inputData = await fs.readFile(`${__dirname}/${process.argv[2]}.txt`);
  const inputs = inputData
    .toString()
    .split('\n')
    .filter((n) => n)
    .map((n) => parseInt(n, 10));

  let offset = 0;
  let sumMax;
  for (let index = 25; index < inputs.length; index++) {
    const element = inputs[index];
    let foundSum = false;
    for (let j = offset; j < index; j++) {
      const sum1 = inputs[j];
      for (let k = j + 1; k < index; k++) {
        const sum2 = inputs[k];
        if (sum1 + sum2 === element) {
          foundSum = true;
        }
      }
    }
    offset++;
    if (!foundSum) {
      console.log('Didnt find', element);
      sumMax = element;
    }
  }

  for (let index = 0; index < inputs.length; index++) {
    const element = inputs[index];
    let goal = sumMax - element;
    const ans = [element];
    for (let j = index + 1; j < inputs.length; j++) {
      const nextElement = inputs[j];
      goal -= nextElement;
      ans.push(nextElement);
      if (goal === 0) {
        ans.sort((a, b) => a - b);
        console.log('part2', ans[0] + ans[ans.length - 1]);
        return;
      }
    }
  }
})();