Solution for part 1.

README.md

@@ -1 +1,14 @@
+# Advent of Code - assignment 9 javascript
 This repository contains answers to the assignments of Advent of Coding 2022
+
+## References
+- https://betterprogramming.pub/tuples-in-javascript-57ede9b1c9d2
+- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/length
+- https://www.javascripttutorial.net/javascript-multidimensional-array/
+- https://flaviocopes.com/how-to-replace-whitespace-javascript/
+- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt
+- https://www.sohamkamani.com/javascript/enums/
+- https://www.w3schools.com/js/js_switch.asp
+- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/sign
+- https://stackoverflow.com/questions/4564414/delete-first-character-of-string-if-it-is-0
+- https://stackoverflow.com/questions/1959040/is-it-possible-to-send-a-variable-number-of-arguments-to-a-javascript-function

script.js

@@ -9,6 +9,127 @@ window.onload = function() {
     document.getElementById(ASSIGNMENT).addEventListener("input", calculateAnswer);
 }
 
+const DIRECTIONS  = {
+  UP: 'U',
+  DOWN: 'D',
+  LEFT: 'L',
+  RIGHT: 'R'
+};
+
+class Knot {
+  constructor(x, y) {
+    this.x=x;
+    this.y=y;
+  }
+}
+/*class Rope {
+  constructor(headX, headY, tailX, tailY) {
+    this.headX = headX;
+    this.headY = headY;
+    this.tailX = tailX;
+    this.tailY = tailY;
+    console.info("Created Rope with head:" + headX + "," + headY + " and tail: " + tailX + "," + tailY);
+  }
+
+  step = function (direction) {
+    let oldHeadX = this.headX;
+    let oldHeadY = this.headY;
+    switch (direction) {
+      case DIRECTIONS.UP:
+        this.headY++;
+        break;
+      case DIRECTIONS.DOWN:
+        this.headY--;
+        break;
+      case DIRECTIONS.LEFT:
+        this.headX--;
+        break;
+      case DIRECTIONS.RIGHT:
+        this.headX++;
+        break;
+      default:
+        console.error("Invalid direction given: " + direction);
+    }
+    this.__correctTail(oldHeadX, oldHeadY);
+  }
+
+  getTailPosition = function () {
+    return "" + this.tailX + "," + this.tailY;
+  }
+
+  __correctTail = function (oldHeadX, oldHeadY) {
+    let absoluteDifferenceX = Math.abs(this.headX - this.tailX);
+    let absoluteDifferenceY = Math.abs(this.headY - this.tailY);
+
+    if (absoluteDifferenceX > 1 || absoluteDifferenceY > 1) {
+      this.tailX = oldHeadX;
+      this.tailY = oldHeadY;
+      console.debug("Corrected tail Position: (" + this.tailX + ", " + this.tailY + "), head position: (" + this.headX + ", " + this.headY + ")");
+    }
+  }
+};*/
+class Rope {
+  constructor(count) {
+    if(count < 2) {
+      console.error("Rope needs at least 2 knots.");
+      return;
+    }
+
+    let knots = [];
+    while(count > 0) {
+      knots.push(new Knot(0,0));
+      count--;
+    }
+
+    this.head = knots[0];
+    this.knots = Array.from(knots).slice(1);
+    this.tail = this.knots[this.knots.length-1];
+    console.info("Created Rope with " + knots.length + " knots.");
+  }
+
+  step = function(direction) {
+    let oldHeadX = this.head.x;
+    let oldHeadY = this.head.y;
+    switch(direction) {
+      case DIRECTIONS.UP:
+        this.head.y++;
+        break;
+      case DIRECTIONS.DOWN:
+        this.head.y--;
+        break;
+      case DIRECTIONS.LEFT:
+        this.head.x--;
+        break;
+      case DIRECTIONS.RIGHT:
+        this.head.x++;
+        break;
+      default:
+        console.error("Invalid direction given: " + direction);
+    }
+    this.__correctTails(oldHeadX, oldHeadY, this.head, this.knots[0], this.knots.slice(1));
+  }
+
+  getTailPosition = function() {
+    return "" + this.tail.x + "," + this.tail.y;
+  }
+
+  __correctTails = function(oldHeadX, oldHeadY, head, tail, tails) {
+    let absoluteDifferenceX = Math.abs(head.x - tail.x);
+    let absoluteDifferenceY = Math.abs(head.y - tail.y);
+    let oldTailX = tail.x;
+    let oldTailY = tail.y;
+
+    if(absoluteDifferenceX > 1 || absoluteDifferenceY > 1) {
+      tail.x = oldHeadX;
+      tail.y = oldHeadY;
+      console.debug("Corrected tail Position: (" + this.tail.x + ", " + this.tail.y + "), head position: (" + this.head.x + ", " + this.head.y + ")");
+    }
+    
+    if(tails.length > 0)
+      this.__correctTails(oldTailX, oldTailY, tail, tails[0], tails.slice(1));
+  }
+};
+
 /**
  * Listener function for input in assignment field.
  * @param event the onInput event 
@@ -29,5 +150,30 @@ function algorithm(assignment) {
     let lines = assignment.trim().split(NEWLINE_CHARACTER);
     console.info("Linecount:" + lines.length);
 
-    // TODO: implement assignment
+    let rope = new Rope(10);
+    let visitedPositions = [rope.getTailPosition()];
+
+    for(let i=0; i<lines.length; i++) {
+      let line = lines[i].replace(/\s/g, ''); // Remove all whitespace
+      let direction = line[0];
+      let count = parseInt(line.substring(1));
+      
+      if(isNaN(count)) { // Validate count
+        console.error("Invalid number in line: " + lines[i]);
+      }
+
+      while(count > 0) {
+        rope.step(direction);
+        let tailPosition = rope.getTailPosition();
+
+        if(!visitedPositions.includes(tailPosition) ) { // Add only unique tailpositions
+          visitedPositions.push(tailPosition);
+        }
+
+        count--;
+      }
+    }
+
+    console.log(visitedPositions);
+    return "Amount of positions for tail: " + visitedPositions.length;
 }