adventofcode2025/03/code.js

import { readFileSync } from 'node:fs';

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

// Part One

console.time("part1");
let sum = 0;

for (const element of inputArray) {
  const length = element.length;
  let firstDigitLocation = 0;
  let firstDigit = 1;
  let lastDigit = 0;

  for (let i = 0; i < length - 1; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > firstDigit) {
      firstDigit = digit;
      firstDigitLocation = i;
    }
  }
  for (let i = firstDigitLocation + 1; i < length; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > lastDigit) {
      lastDigit = digit;
    }
  }
  const joltage = (firstDigit * 10) + lastDigit;
  sum += joltage;
}

console.timeEnd("part1");
console.log(sum);

// Part Two

console.time("part2");
let sum2 = 0;

for (const element of inputArray) {
  const length = element.length;
  let firstDigitLocation = 0;
  let firstDigit = 1;
  let secondDigitLocation = 1;
  let secondDigit = 0;
  let thirdDigitLocation = 2;
  let thirdDigit = 0;
  let fourthDigitLocation = 3;
  let fourthDigit = 0;
  let fifthDigitLocation = 4;
  let fifthDigit = 0;
  let sixthDigitLocation = 5;
  let sixthDigit = 0;
  let seventhDigitLocation = 6;
  let seventhDigit = 0;
  let eighthDigitLocation = 7;
  let eighthDigit = 0;
  let ninthDigitLocation = 8;
  let ninthDigit = 0;
  let tenthDigitLocation = 9;
  let tenthDigit = 0;
  let eleventhDigitLocation = 10;
  let eleventhDigit = 0;
  let lastDigit = 0;

  for (let i = 0; i < length - 11; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > firstDigit) {
      firstDigit = digit;
      firstDigitLocation = i;
    }
  }
  for (let i = firstDigitLocation + 1; i < length - 10; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > secondDigit) {
      secondDigit = digit;
      secondDigitLocation = i;
    }
  }
  for (let i = secondDigitLocation + 1; i < length - 9 ; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > thirdDigit) {
      thirdDigit = digit;
      thirdDigitLocation = i;
    }
  }
  for (let i = thirdDigitLocation + 1; i < length - 8; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > fourthDigit) {
      fourthDigit = digit;
      fourthDigitLocation = i;
    }
  }
  for (let i = fourthDigitLocation + 1; i < length - 7; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > fifthDigit) {
      fifthDigit = digit;
      fifthDigitLocation = i;
    }
  }
  for (let i = fifthDigitLocation + 1; i < length - 6; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > sixthDigit) {
      sixthDigit = digit;
      sixthDigitLocation = i;
    }
  }
  for (let i = sixthDigitLocation + 1; i < length - 5; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > seventhDigit) {
      seventhDigit = digit;
      seventhDigitLocation = i;
    }
  }
  for (let i = seventhDigitLocation + 1; i < length - 4; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > eighthDigit) {
      eighthDigit = digit;
      eighthDigitLocation = i;
    }
  }
  for (let i = eighthDigitLocation + 1; i < length - 3; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > ninthDigit) {
      ninthDigit = digit;
      ninthDigitLocation = i;
    }
  }
  for (let i = ninthDigitLocation + 1; i < length - 2; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > tenthDigit) {
      tenthDigit = digit;
      tenthDigitLocation = i;
    }
  }
  for (let i = tenthDigitLocation + 1; i < length - 1; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > eleventhDigit) {
      eleventhDigit = digit;
      eleventhDigitLocation = i;
    }
  }
  for (let i = eleventhDigitLocation + 1; i < length; i++) {
    const digit = Number.parseInt(element[i]);
    if (digit > lastDigit) {
      lastDigit = digit;
    }
  }

  const joltage = (firstDigit * 100000000000) +
                  (secondDigit * 10000000000) +
                    (thirdDigit * 1000000000) +
                    (fourthDigit * 100000000) +
                      (fifthDigit * 10000000) +
                       (sixthDigit * 1000000) +
                      (seventhDigit * 100000) +
                        (eighthDigit * 10000) +
                          (ninthDigit * 1000) +
                           (tenthDigit * 100) +
                         (eleventhDigit * 10) +
                         lastDigit;
  sum2 += joltage;
}

console.timeEnd("part2");
console.log(sum2);
// functions