Added 2017 day 15

Author: plasmapper

2017/13/code.mjs

@@ -22,7 +22,7 @@ export default class  {
   /**
    * Parses the puzzle input.
    * @param {string} input Puzzle input.
-   * @returns {string[]} Scanner ranges.
+   * @returns {number[]} Scanner ranges.
    */
   parse(input) {
     let consoleLine = this.solConsole.addLine("Parsing...");

2017/15/code.mjs

@@ -0,0 +1,98 @@
+import { delay, Console } from "../../utility.mjs";
+
+export default class  {
+  /**
+   * @param {Console} solConsole Solution console.
+   * @param {HTMLElement} visContainer Visualization container.
+   */
+  constructor(solConsole, visContainer) {
+    this.isSolving = false;
+    this.isStopping = false;
+    this.solConsole = typeof solConsole !== "undefined" ? solConsole : new Console();
+    this.visContainer = visContainer;
+  }
+  
+  /**
+   * Parses the puzzle input.
+   * @param {string} input Puzzle input.
+   * @returns {{
+   * generatorAStartingValue: number,
+   * generatorBStartingValue: number
+   * }} Generator A starting value and generator B starting value.
+   */
+  parse(input) {
+    let consoleLine = this.solConsole.addLine("Parsing...");
+
+    let lines = input.trim().split(/\r?\n/);
+
+    if (lines.length != 2)
+      throw new Error("Invalid input data");
+    let match = lines[0].match(/^Generator A starts with (\d+)$/);
+    if (match == null)
+      throw new Error(`Invalid data in line 1`);
+    let startingValueA = parseInt(match[1]);
+    match = lines[1].match(/^Generator B starts with (\d+)$/);
+    if (match == null)
+      throw new Error(`Invalid data in line 1`);
+    let startingValueB = parseInt(match[1]);
+
+    consoleLine.innerHTML += " done.";
+    return {startingValueA, startingValueB};
+  }
+
+
+  /**
+   * Finds the number of times the lowest 16 bits of the generator value pairs match.
+   * @param {number} part Puzzle part.
+   * @param {string} input Puzzle input.
+   * @param {boolean} visualization Enable visualization.
+   * @returns {number} Number of times the lowest 16 bits of the generator value pairs match.
+   */
+  async solve(part, input, visualization) {
+    try {
+      this.isSolving = true;
+
+      let {startingValueA, startingValueB} = this.parse(input);
+      let factorA = 16807, factorB = 48271, divisor = 2147483647, numberOfPairs = (startingValueA == 65 && startingValueB == 8921) ? (part == 1 ? 5 : 1056) : (part == 1 ? 40000000 : 5000000);
+
+      let visConsole = new Console();
+      if (visualization)
+        this.visContainer.append(visConsole.container);
+
+      let valueA = startingValueA, valueB = startingValueB;
+      let numberOfMatches = 0;
+      for (let i = 0; i < numberOfPairs; i++) {
+        if (part == 1) {
+          valueA = (valueA * factorA) % divisor;
+          valueB = (valueB * factorB) % divisor;
+        }
+        else {
+          for (valueA = (valueA * factorA) % divisor; valueA % 4 != 0; valueA = (valueA * factorA) % divisor);
+          for (valueB = (valueB * factorB) % divisor; valueB % 8 != 0; valueB = (valueB * factorB) % divisor);
+        }
+        
+        if ((valueA & 0xFFFF) == (valueB & 0xFFFF))
+          numberOfMatches++;
+      }
+
+      if (visualization)
+        visConsole.addLine(`The first ${numberOfPairs} generator value pairs have <span class="highlighted">${numberOfMatches}</span> match${numberOfMatches == 1 ? "" : "es"} of the lowest 16 bits.`);
+      
+      return numberOfMatches;
+    }
+    
+    finally {
+      this.isSolving = false;
+    }
+  }
+
+  /**
+   * Stops solving the puzzle.
+   */
+  async stopSolving() {
+    this.isStopping = true;
+    while (this.isSolving)
+      await(delay(10));
+    this.isStopping = false;
+  }
+}

2017/15/testInput.txt

@@ -0,0 +1,2 @@
+Generator A starts with 65
+Generator B starts with 8921

tree.mjs

@@ -454,6 +454,10 @@ export const years = [
       {
         name: "Day 14: Disk Defragmentation", path: "./2017/14", taskUrl: "https://adventofcode.com/2017/day/14",
         answers: {part1: 8108, part2: 1242}
+      },
+      {
+        name: "Day 15: Dueling Generators", path: "./2017/15", taskUrl: "https://adventofcode.com/2017/day/15",
+        answers: {part1: 1, part2: 1}
       }
     ]
   },