Adv2018/d17/main.js

function readAll(cb) {
    require("fs").readFile('./input', 'utf8', (err, data) => {
        var world = new World();
        data.split("\n").forEach(line => {
            if (!line)
                return;
            var numbers = line.match(/(\d+)/g).map(i => parseInt(i));
            if (line.charAt(0) == 'x')
                world.addData(numbers[0], numbers[0], numbers[1], numbers[2], 'x');
            else
                world.addData(numbers[1], numbers[2], numbers[0], numbers[0], 'x');
        });
        cb(world);
    });
}

function World() {
    this.data = {};
    this.sources = [[ 500, 0 ]];
    this.minX = 500;
    this.maxX = 500;
    this.minY = 0;
    this.maxY = 0;
}

World.prototype.addData = function(x1, x2, y1, y2, type) {
    while (y1 <= y2) {
        for (var j = x1; j <= x2; ++j) {
            this.data[y1] = this.data[y1] || {};
            this.data[y1][j] = type;
        }
        ++y1;
    }
    this.minX = Math.min(x1, this.minX);
    this.maxX = Math.max(x2, this.maxX);
    if (type == 'x') {
        this.minY = Math.min(y1, this.minY);
        this.maxY = Math.max(y2, this.maxY);
    }
}

World.prototype.getChar = function(x, y, defaultValue) {
    return this.data[y] ? this.data[y][x] || defaultValue : defaultValue;
}

World.prototype.isEmpty = function(x, y) {
    var c = this.getChar(x, y, false);
    return !c || c == '|';
}

World.prototype.nextClay = function(x, y, direction) {
    for (; x >= this.minX && x <= this.maxX; x += direction) {
        if (this.isEmpty(x, y +1))
            return false;
        if (!this.isEmpty(x, y))
            return x;
    }
    return false;
}

World.prototype.trySettle = function(minX, maxX, y) {
    if (minX === false || maxX === false || minX === maxX)
        return false;
    this.addData(minX +1, maxX -1, y, y, '~');
    return true;
}

World.prototype.water = function() {
    var x = this.sources[0][0],
        y = this.sources[0][1];
    while (this.isEmpty(x, y +1) && y <= this.maxY)
        ++y;
    if (y <= this.maxY) {
        var minX = this.nextClay(x, y, -1),
            maxX = this.nextClay(x, y, +1);
        if (this.trySettle(minX, maxX, y))
            return;
        var found = false;
        for (var tmp = x; this.isEmpty(tmp, y); ++tmp) {
            this.addData(tmp, tmp, y, y, '|');
            if (this.isEmpty(tmp, y +1)) {
                this.sources.push([ tmp, y ]);
                break;
            }
        }
        for (var tmp = x; this.isEmpty(tmp, y); --tmp) {
            this.addData(tmp, x, y, y, '|');
            if (this.isEmpty(tmp, y +1)) {
                this.addData(tmp, x, y, y, '|');
                this.sources.push([ tmp, y ]);
                break;
            }
        }
    }
    this.addData(x, x, this.sources[0][1], y, '|');
    this.sources.splice(0, 1);
}

World.prototype.countWater = function() {
    var count = { settled: 0, unsettled: 0 };
    for (var i in this.data)
        if (i != 0)
            for (var j in this.data[i])
                switch (this.data[i][j]) {
                    case '~':
                        ++count.settled;
                        break;
                    case '|':
                        ++count.unsettled;
                        break;
                }
    count.total = count.settled +count.unsettled;
    return count;
}

World.prototype.print = function() {
    for (var i =this.minY; i <= this.maxY; ++i) {
        for (var j =this.minX; j <= this.maxX; ++j)
            process.stdout.write(this.getChar(j, i, ' '));
        process.stdout.write("\n");
    }
}

function run() {
    readAll(world => {
        while (world.sources.length)
            world.water();
        //world.print();
        console.log("Water cell: ", world.countWater());
    });
}

run();