AoC day 9 part 1 solution

const fs = require('fs');

const data = fs
    .readFileSync('./input.txt')
    .toString()
    .trim()
    .replace(/\r/g, '')
    .split('')
    .map(Number);

const unpackedDisk = [];

for (let i = 0; i < data.length; i++) {
    for (let j = data[i]; j > 0; j--) {
        if (i % 2 === 0) {
            unpackedDisk.push(i / 2);
        } else {
            unpackedDisk.push('.');
        }
    }
}

// defrag
unpackedDisk.forEach((block, index, arr) => {
    if (block === '.') {
        while (true) {
            const temp = arr.pop();
            if (temp === '.') {
                continue;
            } else {
                arr[index] = temp;
                break;
            }
        }
    }
});

let checksum = 0;

unpackedDisk.forEach((block, id) => {
    checksum += block * id;
});

console.log(checksum);