AoC/2024/15/index2.ts

const fs = require('fs');

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

interface Coord {
    x: number,
    y: number,
};

let [mapStr, movementsStr] = input.split("\n\n");
mapStr = mapStr.replace(/([#.])/g, '$1$1').replaceAll('O', '[]').replaceAll('@', '@.');

const map: Array<Array<string>> = mapStr.split("\n").map((row: string) => row.split(''))
const movements = movementsStr.split("\n").join('');

const width = map[0].length;
const height = map.length;

const robotIndex = mapStr.indexOf('@');
let robotPos = { x: robotIndex % (width + 1), y: Math.floor(robotIndex / width) };
map[robotPos.y][robotPos.x] = '.';

function nextCoord(pos: Coord, dir: '^'|'>'|'<'|'v'): Coord {
    return {
        "^": { x: pos.x, y: pos.y - 1 },
        ">": { x: pos.x + 1, y: pos.y },
        "v": { x: pos.x, y: pos.y + 1 },
        "<": { x: pos.x - 1, y: pos.y },
    }[dir];
}

function printMap() {
    const mapClone = map.slice().map((row: Array<string>) => row.slice());
    mapClone[robotPos.y][robotPos.x] = '@';
    console.log(mapClone.map((row: Array<string>) => row.join('')).join("\n"));
}

printMap();

function get(coord: Coord) {
    return map[coord.y][coord.x];
}

function set(coord: Coord, val: string) {
    return map[coord.y][coord.x] = val;
}

function canPushBox(leftPart: Coord, dir: '^'|'>'|'<'|'v'): boolean {
    if (dir === '<') {
        const next = nextCoord(leftPart, dir);
        const val = get(next);
        if (val === '#') {
            return false;
        }
        if (val === ']') {
            const movedNext = canPushBox(nextCoord(next, dir)!, dir);
            if (!movedNext) {
                return false;
            }
        }
        return true;
    }
    const rightPart = nextCoord(leftPart, '>');
    if (dir === '>') {
        const next = nextCoord(rightPart, dir);
        const val = get(next);
        if (val === '#') {
            return false;
        }
        if (val === '[') {
            const movedNext = canPushBox(next, dir);
            if (!movedNext) {
                return false;
            }
        }
        return true;
    }
    const nextLeft = nextCoord(leftPart, dir);
    const nextRight = nextCoord(rightPart, dir);
    const nextLeftVal = get(nextLeft);
    const nextRightVal = get(nextRight);
    if (nextLeftVal === '#' || nextRightVal === '#') {
        return false;
    }
    if (nextLeftVal === '[' || nextLeftVal === ']') {
        const movedNext = canPushBox(nextLeftVal === '[' ? nextLeft : nextCoord(nextLeft, '<'), dir);
        if (!movedNext) {
            return false;
        }
    }
    if (nextRightVal === '[') {
        const movedNext = canPushBox(nextRight, dir);
        if (!movedNext) {
            return false;
        }
    }
    return true;
}

function pushBox(leftPart: Coord, dir: '^'|'>'|'<'|'v') {
    if (dir === '<') {
        const next = nextCoord(leftPart, dir);
        const val = get(next);
        if (val === ']') {
            pushBox(nextCoord(next, dir)!, dir);
        }
        set(next, '[');
        set(leftPart, ']');
        set(nextCoord(leftPart, '>')!, '.');
        return;
    }
    const rightPart = nextCoord(leftPart, '>');
    if (dir === '>') {
        const next = nextCoord(rightPart, dir);
        const val = get(next);
        if (val === '[') {
            pushBox(next, dir);
        }
        set(rightPart, '[');
        set(next, ']');
        set(leftPart, '.');
        return;
    }
    const nextLeft = nextCoord(leftPart, dir);
    const nextRight = nextCoord(rightPart, dir);
    const nextLeftVal = get(nextLeft);
    const nextRightVal = get(nextRight);
    if (nextLeftVal === '[' || nextLeftVal === ']') {
        pushBox(nextLeftVal === '[' ? nextLeft : nextCoord(nextLeft, '<'), dir);
    }
    if (nextRightVal === '[') {
        pushBox(nextRight, dir);
    }
    set(nextLeft, '[');
    set(nextRight, ']');
    set(leftPart, '.');
    set(rightPart, '.');
}

function sleep() {
    const promise: Promise<void> = new Promise((resolve) => {
        setTimeout(() => resolve(), 50);
    });
    return promise;
}

async function go() {
    for (let i = 0; i < movements.length; i++) {
        const direction = movements[i];

        const nextRobotPosition = nextCoord(robotPos, direction);
        let value = get(nextRobotPosition);
        if (value === '#') {
            printMap();
            continue;
        }
        if (value === '[' || value === ']') {
            const leftBoxCoord = value === '[' ? nextRobotPosition : nextCoord(nextRobotPosition, '<');
            if (canPushBox(leftBoxCoord, direction)) {
                pushBox(leftBoxCoord, direction);
            } else {
                printMap();
                continue;
            }
        }
        robotPos = nextRobotPosition;
        printMap();
        await sleep();
    }

    let sum = 0;

    map.forEach((row, y) => {
        row.forEach((val, x) => {
            if (val === '[') {
                sum += ((y * 100) + x);
            }
        });
    });

    console.log(sum);
}

go();