advent2022/d14/main.js

const fs = require('fs');
const readline = require('readline');

function RockLine(from, to) {
    this.from = [];
    this.to = [];
    if (from[0] === to[0])
    {
        this.from[1] = Math.min(from[1], to[1]);
        this.to[1] = Math.max(from[1], to[1]);
        this.from[0] = this.to[0] = from[0];
    } else {
        this.from[0] = Math.min(from[0], to[0]);
        this.to[0] = Math.max(from[0], to[0]);
        this.from[1] = this.to[1] = from[1];
    }
}

RockLine.prototype.contains = function(pos) {
    if (this.from[0] === this.to[0])
        return pos[0] === this.from[0] && pos[1] >= this.from[1] && pos[1] <= this.to[1];
    return pos[1] === this.from[1] && pos[0] >= this.from[0] && pos[0] <= this.to[0];
}

function Map() {
    this.rockLines = [];
    this.sand = [];
    this.bottom = 0;
}

Map.prototype.canMove = function(pos) {
    return !this.sand.find(i => i[0] === pos[0] && i[1] === pos[1]) && !this.rockLines.find(i => i.contains(pos));
}

Map.prototype.moveSand = function() {
    const index = this.sand.length -1;
    if (this.sand[index][1] > this.bottom)
        return false;
    if (this.canMove([this.sand[index][0], this.sand[index][1]+1])) {
        this.sand[index][1]++;
    } else if (this.canMove([this.sand[index][0]-1, this.sand[index][1]+1])) {
        this.sand[index][0]--;
        this.sand[index][1]++;
    } else if (this.canMove([this.sand[index][0]+1, this.sand[index][1] +1])) {
        this.sand[index][0]++;
        this.sand[index][1]++;
    }
    else
        return false;
    return true;
}

Map.prototype.round = function(infiniteGround) {
    if (!this.canMove([500, 0]))
        return false;
    this.sand.push([500, 0]);
    while (this.moveSand());
    return infiniteGround ? this.sand.slice(-1)[0][1] < this.bottom : true;
}

async function main() {
    let map = new Map();
    for await (let line of readline.createInterface({ input: process.stdin })) {
        let lines = line.split(' -> ').map(i => i.split(',').map(i => parseInt(i)));
        for (let i =1; i < lines.length; ++i)
            map.rockLines.push(new RockLine(lines[i -1], lines[i]));
    }
    map.bottom = map.rockLines.map(i => Math.max(i.from[1], i.to[1])).reduce((i, j) => Math.max(i||0, j));
    while (map.round(true));
    console.log(map.sand.length -1);
    while (map.round(false));
    console.log(map.sand.length);
};

(main());