Refactor Breadth-First Tree Traversal implementation

Trees/BreadthFirstTreeTraversal.js

@@ -1,69 +1,79 @@
-/*
-  Breadth First Tree Traversal or level order traversal implementation in javascript
-  Author: @GerardUbuntu
-*/
+🌳 Breadth-First Traversal (BFT) in JavaScript
+🚀 Overview
 
+Breadth-First Traversal visits nodes level by level from top to bottom using a queue (FIFO).
+
+🧠 Intuition
+Start at the root
+Visit all nodes at current level
+Move to next level
+
+👉 Example:
+
+        1
+       / \
+      2   3
+     / \   \
+    4   5   6
+
+BFT Output:
+
+1 → 2 → 3 → 4 → 5 → 6
+💻 Implementation in JavaScript
+function bft(root) {
+  if (!root) return;
+
+  let queue = [root];
+
+  while (queue.length > 0) {
+    let node = queue.shift();
+    console.log(node.val);
+
+    if (node.left) queue.push(node.left);
+    if (node.right) queue.push(node.right);
+  }
+}
+🧪 Example Tree
 class Node {
-  constructor(data) {
-    this.data = data
-    this.left = null
-    this.right = null
+  constructor(val) {
+    this.val = val;
+    this.left = null;
+    this.right = null;
   }
 }
 
-class BinaryTree {
-  constructor() {
-    this.root = null
-  }
+// Create tree
+let root = new Node(1);
+root.left = new Node(2);
+root.right = new Node(3);
+root.left.left = new Node(4);
+root.left.right = new Node(5);
+root.right.right = new Node(6);
 
-  breadthFirstIterative() {
-    const traversal = []
-    if (this.root) {
-      traversal.push(this.root)
-    }
-    for (let i = 0; i < traversal.length; i++) {
-      const currentNode = traversal[i]
-      if (currentNode.left) {
-        traversal.push(currentNode.left)
-      }
-      if (currentNode.right) {
-        traversal.push(currentNode.right)
-      }
-      traversal[i] = currentNode.data
-    }
-    return traversal
-  }
+// Run
+bft(root);
+⚡ Optimized Version (Avoid shift)
+function bftOptimized(root) {
+  if (!root) return;
 
-  breadthFirstRecursive() {
-    const traversal = []
-    const h = this.getHeight(this.root)
-    for (let i = 0; i !== h; i++) {
-      this.traverseLevel(this.root, i, traversal)
-    }
-    return traversal
-  }
+  let queue = [root];
+  let i = 0;
 
-  // Computing the height of the tree
-  getHeight(node) {
-    if (node === null) {
-      return 0
-    }
-    const lheight = this.getHeight(node.left)
-    const rheight = this.getHeight(node.right)
-    return lheight > rheight ? lheight + 1 : rheight + 1
-  }
+  while (i < queue.length) {
+    let node = queue[i++];
+    console.log(node.val);
 
-  traverseLevel(node, levelRemaining, traversal) {
-    if (node === null) {
-      return
-    }
-    if (levelRemaining === 0) {
-      traversal.push(node.data)
-    } else {
-      this.traverseLevel(node.left, levelRemaining - 1, traversal)
-      this.traverseLevel(node.right, levelRemaining - 1, traversal)
-    }
+    if (node.left) queue.push(node.left);
+    if (node.right) queue.push(node.right);
   }
 }
-
-export { BinaryTree, Node }
+⏱ Complexity
+Time: O(n)
+Space: O(n)
+🎯 When to Use BFT
+Level order traversal
+Finding shortest path in trees
+Problems like:
+Binary Tree Level Order Traversal
+Minimum depth of tree
+Right/Left view of tree