Add invert-binary-tree solution

Author: Jeehay28

invert-binary-tree/Jeehay28.js

@@ -0,0 +1,91 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+
+// ✔️ Recursive Approach
+// Time Complexity: O(N), N = Total number of nodes (each node is processed once)
+// Space Complexity: O(H), H = Height of the tree (due to recursion stack depth)
+
+var invertTree = function (root) {
+  if (!root) return null;
+
+  [root.left, root.right] = [root.right, root.left];
+
+  invertTree(root.left);
+  invertTree(root.right);
+
+  return root;
+};
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+
+// ✔️ Stack → DFS approach
+// Time Complexity: O(N), N = Total number of nodes (each node is processed once)
+// Space Complexity: O(H), H = Height of the tree (due to recursion stack depth)
+
+// var invertTree = function (root) {
+//   let stack = [root];
+
+//   while (stack.length > 0) {
+//     const node = stack.pop();
+//     if (!node) continue;
+
+//     [node.left, node.right] = [node.right, node.left];
+//     stack.push(node.left);
+//     stack.push(node.right);
+//   }
+//   return root;
+// };
+
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+
+// ✔️ Queue → BFS
+// Time Complexity: O(N), N = Total number of nodes (each node is processed once)
+// Space Complexity: O(W), W = Maximum width of the tree
+// var invertTree = function (root) {
+//   let queue = [root];
+
+//   while (queue.length > 0) {
+//     const node = queue.shift();
+//     if (!node) continue;
+
+//     [node.left, node.right] = [node.right, node.left];
+//     queue.push(node.left);
+//     queue.push(node.right);
+//   }
+//   return root;
+// };
+
+