Day 6 part 2

day-6/main.js

@@ -28,23 +28,66 @@ function getInput() {
   return data;
 }
 
-function part1() {
+function getStart(data) {
-  let data = getInput();
   const HEIGHT = data.length;
-  const WIDTH = data[0].length;
-  let currentDir = DIRECTIONS.UP;
-
   let actualPos = { x: 0, y: 0 };
 
-  // Search initial pos
   for (let y = 0; y < HEIGHT; y++) {
     const x = data[y].indexOf("^");
     if (x == -1) continue;
-    data[y][x] = "X";
     actualPos.y = y;
     actualPos.x = x;
   }
-  // console.log(actualPos);
+  return actualPos;
+}
+
+function detectLoop(obstacle) {
+  let data = getInput();
+  data[obstacle[0]][obstacle[1]] = "#";
+  let currentDir = DIRECTIONS.UP;
+  let actualPos = getStart(data);
+  data[actualPos.y][actualPos.x] = ".";
+  let counter = 1;
+  let nextStep = null;
+  let newX = null;
+  let newY = null;
+  while (true) {
+    switch (currentDir) {
+      case DIRECTIONS.UP:
+        newY = actualPos.y - 1;
+        newX = actualPos.x;
+        break;
+      case DIRECTIONS.DOWN:
+        newY = actualPos.y + 1;
+        newX = actualPos.x;
+        break;
+      case DIRECTIONS.LEFT:
+        newY = actualPos.y;
+        newX = actualPos.x - 1;
+        break;
+      case DIRECTIONS.RIGHT:
+        newY = actualPos.y;
+        newX = actualPos.x + 1;
+        break;
+    }
+    nextStep = (data[newY] ?? [])[newX];
+    if (nextStep == undefined) return false;
+    if (nextStep == ".") {
+      // data[newY][newX] = "X";
+      actualPos.y = newY;
+      actualPos.x = newX;
+      counter++;
+      if (counter >= 20000) return true;
+    } else {
+      currentDir = rotate(currentDir);
+    }
+  }
+}
+
+function part1(data = getInput()) {
+  let currentDir = DIRECTIONS.UP;
+  let actualPos = getStart(data);
+  data[actualPos.y][actualPos.x] = "X";
 
   // Start algorithm
   let counter = 1;
@@ -89,4 +132,32 @@ function part1() {
   // console.log(data.map((line) => line.join("")).join("\n"));
 }
 
+function part2() {
+  let data = getInput();
+
+  let actualPos = getStart(data);
+
+  let possibleObstacle = [];
+  for (let y in data) {
+    for (let x in data) {
+      if (data[y][x] == "." || (y != actualPos.y && x != actualPos.x)) {
+        possibleObstacle.push([y, x]);
+      }
+    }
+  }
+
+  let counter = 0;
+  for (const obstacle of possibleObstacle) {
+    let innerData = getInput();
+    if (detectLoop(obstacle)) {
+      counter++;
+    }
+  }
+  console.log(counter);
+}
+
+console.log("Part 1:");
 part1();
+
+console.log("Part 2:");
+part2();