Merge pull request #3588 from aadil42/patch-114

Create 0103-binary-tree-zigzag-level-order-traversal.js

Author: Ykhan799

javascript/0103-binary-tree-zigzag-level-order-traversal.js

@@ -0,0 +1,41 @@
+/**
+ * BFS
+ * Time O(N) | Space O(N)
+ * https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var zigzagLevelOrder = (root) => {
+    const isEdgeBase = (root === null);
+    if (isEdgeBase) return [];
+    
+    return search(root);/* Time O(N) | Space O(N) */
+};
+
+var search = (root, isZigZag = true, order = []) => {
+    const queue = new Queue([ root ]);
+    
+    while (!queue.isEmpty()) {        /* Time O(N) */
+        const levels = [];
+
+        bfs(queue, isZigZag, levels); /* Time O(WIDTH) | Space O(WIDTH) */
+        order.push(levels);           /*                 Space O(N) */
+        isZigZag = !isZigZag;
+    }
+    
+    return order;
+}
+
+const bfs = (queue, isZigZag, levels) => {
+    for (let level = queue.size(); (0 < level); level--) {/* Time O(WIDTH) */
+        const { left, val, right } = queue.dequeue();
+    
+        if (left) queue.enqueue(left);  /* Space O(WIDTH) */
+        if (right) queue.enqueue(right);/* Space O(WIDTH) */
+        
+        levels.push(val);               /* Space O(N) */
+    }
+
+    if (!isZigZag) levels.reverse();
+}
+