AoC/2024/17/index.ts

const fs = require('fs');

const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');

const lines = input.split("\n");

let registerA = BigInt(parseInt(lines[0].split(' ')[2]));
let registerB = BigInt(parseInt(lines[1].split(' ')[2]));
let registerC = BigInt(parseInt(lines[2].split(' ')[2]));

let output: Array<string> = [];

let instructionsStr = lines[4].split(' ')[1];
const instructions = instructionsStr.split(',').map((i: string) => parseInt(i));

let pointer = 0;

function combo(op: bigint): bigint {
    if (op <= 3n) {
        return op;
    }
    if (op === 4n) {
        return registerA;
    }
    if (op === 5n) {
        return registerB;
    }
    if (op === 6n) {
        return registerC;
    }
    return op;
}

function call(ins: number, op: number) {
    let bop = BigInt(op);
    if (ins === 0) {
        bop = combo(bop);
        registerA = registerA >> bop;
        return;
    }
    if (ins === 1) {
        registerB ^= bop;
        return;
    }
    if (ins === 2) {
        bop = combo(bop);
        registerB = bop & 7n;
        return;
    }
    if (ins === 4) {
        registerB ^= registerC;
        return;
    }
    if (ins === 5) {
        bop = combo(bop);
        output.push(''+(bop & 7n));
        return;
    }
    if (ins === 6) {
        bop = combo(bop);
        registerB = registerA >> bop;
        return;
    }
    if (ins === 7) {
        bop = combo(bop);
        registerC = registerA >> bop;
        return;
    }
}

function printPC() {
    console.log(`
A: ${registerA}
B: ${registerB}
C: ${registerC}

ins: ${typeof instructions[pointer] !== 'undefined' ? instructions[pointer] : 'NA'}
op: ${typeof instructions[pointer+1] !== 'undefined' ? instructions[pointer+1] : 'NA'}
combo: ${typeof instructions[pointer+1] !== 'undefined' ? combo(instructions[pointer+1]) : 'NA'}

Output: ${output}
`);
}

function run() {
    while (pointer < instructions.length) {
        const ins = instructions[pointer];
        const op = instructions[pointer + 1];

        if (ins === 3) {
            pointer = registerA === 0n ? pointer + 2 : op;
        } else {
            call(ins, op);
            pointer += 2;
        }
    }
}

run();
console.log(output.join(','));