214 lines
4.8 KiB
JavaScript
214 lines
4.8 KiB
JavaScript
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import * as fs from "fs";
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function load(filename) {
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let data = fs.readFileSync(filename, "utf8").trim();
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const l = data.length;
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let i = 0;
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return {
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next: function () {
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const c = data[i];
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i = (i + 1) % l;
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return c;
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}
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};
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}
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const masks = [
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0b1000000,
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0b0100000,
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0b0010000,
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0b0001000,
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0b0000100,
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0b0000010,
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0b0000001,
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];
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const shapes = [
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[0b0011110],
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[0b0001000, 0b0011100, 0b0001000],
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[0b0000100, 0b0000100, 0b0011100],
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[0b0010000, 0b0010000, 0b0010000, 0b0010000],
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[0b0011000, 0b0011000],
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];
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const shapes_len = shapes.length;
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class Shape {
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constructor(shape) {
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this.shape = shape;
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this.length = shape.length;
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}
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fall(field) { // returns true if the shape fell without colliding
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for (let i=0; i<this.length; ++i) {
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const next = field.get(i+1);
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if (next === undefined || next & this.shape[i]) { //collision
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field.solidify(this.shape);
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return false;
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}
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}
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field.fall();
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return true;
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}
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shift(field, direction) {
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let collision = false;
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let tmp;
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switch(direction) {
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case ">":
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tmp = this.shape.map(line => {
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if (line & 0b1) { // we touch the right edge already
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collision = true;
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}
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return line >>> 1;
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});
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break;
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case "<":
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tmp = this.shape.map(line => {
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if (line & 0b1000000) { // we touch the left edge already
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collision = true;
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}
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return line << 1;
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});
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break;
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default:
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throw "invalid direction character in shape shift: " + direction;
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}
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if (collision) {
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return;
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}
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for (let i=0; i<this.length; ++i) {
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if (field.get(i) & tmp[i]) { //collision
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return;
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}
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}
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this.shape = tmp;
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}
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print() {
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this.shape.forEach(line => {
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console.log(
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line & 0b1000000 ? "#" : ".",
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line & 0b0100000 ? "#" : ".",
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line & 0b0010000 ? "#" : ".",
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line & 0b0001000 ? "#" : ".",
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line & 0b0000100 ? "#" : ".",
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line & 0b0000010 ? "#" : ".",
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line & 0b0000001 ? "#" : ".",
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);
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});
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console.log("=======");
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}
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}
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class Shaper {
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constructor() {
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this.index = 0;
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}
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next(field) {
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const s = new Shape(shapes[this.index]);
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field.accomodate(shapes[this.index].length + 3);
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this.index = (this.index + 1) % shapes_len;
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return s;
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}
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}
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class Field {
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constructor() {
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this.data = [];
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this.offset = 0;
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}
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accomodate(n) {
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this.offset = 0;
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for(let i=0; i<n; ++i) {
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this.data.unshift(0);
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}
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}
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fall() {
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if (this.data[0] !== 0) { // we need to fall bellow the top line?
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this.offset++;
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} else {
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this.data.shift();
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}
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}
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get(offset) {
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return this.data[this.offset + offset];
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}
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heightMap() {
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const max = this.data.length;
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let heights = [max, max, max, max, max, max, max];
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heights.forEach((h, i) => {
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for(let j=0; j<this.data.length; ++j) {
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if (this.data[j] & masks[i]) {
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heights[i] = j;
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break;
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}
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}
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});
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return heights;
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}
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print() {
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this.data.forEach(line => {
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console.log(
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line & 0b1000000 ? "#" : ".",
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line & 0b0100000 ? "#" : ".",
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line & 0b0010000 ? "#" : ".",
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line & 0b0001000 ? "#" : ".",
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line & 0b0000100 ? "#" : ".",
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line & 0b0000010 ? "#" : ".",
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line & 0b0000001 ? "#" : ".",
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);
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});
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console.log("-------");
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}
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solidify(shape) {
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for(let i=0; i<shape.length; ++i) {
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this.data[i+this.offset] |= shape[i];
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}
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}
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}
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let example = load("example");
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let input = load("input");
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function solve(input) {
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let field = new Field();
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let shaper = new Shaper();
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let height = 0;
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let heightmaps = [];
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const sky = 1000000000000;
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for(let i=0; i<sky; ++i) {
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let shape = shaper.next(field);
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do {
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shape.shift(field, input.next());
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} while(shape.fall(field));
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const heightmap = field.heightMap();
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let cycle = -1;
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let cycleHeight = 0;
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heightmaps.forEach((h, n) => {
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if (h.heightmap.every((v, idx) => v === heightmap[idx])) {
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let nextCycle = heightmaps[(n+1)*2-1];
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if (nextCycle !== undefined && nextCycle.heightmap.every((v, idx) => v === heightmap[idx])) {
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let nextCycle2 = heightmaps[(n+1)*3-1];
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if (nextCycle2 !== undefined && nextCycle2.heightmap.every((v, idx) => v === heightmap[idx])) {
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cycle = n+1;
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cycleHeight = field.data.length - h.height;
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}
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}
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}
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});
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if (cycle > 0) {
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console.log("got cycle of", cycle, "with a height of", cycleHeight, "after", i, "iterations");
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const cycles = Math.floor((sky - i) / cycle);
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i += cycles * cycle;
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height = cycles * cycleHeight;
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console.log("computed a height of", height, "after", cycles * cycle, "additional cycles");
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heightmaps = [];
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}
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heightmaps.unshift({ heightmap: heightmap, height: field.data.length });
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}
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return height + field.data.length;
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}
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const exampleOutput = solve(example);
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if (exampleOutput !== 1514285714288) {
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console.log("Example failed with height " + exampleOutput, "diff is", exampleOutput - 1514285714288, "positive means too high");
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process.exit(1); // eslint-disable-line
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}
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console.log(solve(input));
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