Add maximum-depth-of-binary-tree solution in TypeScript

Author: Jeehay28

maximum-depth-of-binary-tree/Jeehay28.ts

@@ -0,0 +1,75 @@
+class TreeNode {
+  val: number;
+  left: TreeNode | null;
+  right: TreeNode | null;
+  constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+    this.val = val === undefined ? 0 : val;
+    this.left = left === undefined ? null : left;
+    this.right = right === undefined ? null : right;
+  }
+}
+
+// Approach 3:
+// Time Complexity: O(n)
+// Space Complexity: O(n), due to the recursion stack
+
+function maxDepth(root: TreeNode | null): number {
+  if (!root) return 0;
+
+  return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
+}
+
+// Approach 2:
+// Time Complexity: O(n)
+// Space Complexity: O(n)
+
+// function maxDepth(root: TreeNode | null): number {
+//   if (!root) return 0;
+
+//   let maxDepth = 0;
+//   let stack: Array<[TreeNode, number]> = [[root, 1]];
+
+//   while (stack.length > 0) {
+//     const item = stack.pop();
+
+//     if (!item) continue;
+
+//     const [node, depth] = item;
+
+//     maxDepth = Math.max(maxDepth, depth);
+
+//     if (node.left) {
+//       stack.push([node.left, depth + 1]);
+//     }
+
+//     if (node.right) {
+//       stack.push([node.right, depth + 1]);
+//     }
+//   }
+
+//   return maxDepth;
+// }
+
+
+// Approach 1
+// Time Compleixty:O(n)
+// Space Complexity:O(n), due to the recursion stack
+
+// function maxDepth(root: TreeNode | null): number {
+//   let maxCnt = 0;
+
+//   const dfs = (node: TreeNode | null, cnt: number) => {
+//     if (!node) {
+//       maxCnt = Math.max(maxCnt, cnt);
+//       return;
+//     }
+
+//     dfs(node.left, cnt + 1);
+//     dfs(node.right, cnt + 1);
+//   };
+
+//   dfs(root, 0);
+
+//   return maxCnt;
+// }
+