Feat: 104. Maximum Depth of Binary Tree

Author: HC-kang

maximum-depth-of-binary-tree/HC-kang.ts

@@ -0,0 +1,55 @@
+// 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;
+//   }
+// }
+
+/**
+ * https://leetcode.com/problems/maximum-depth-of-binary-tree
+ * using recursion
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function maxDepth(root: TreeNode | null): number {
+  return dfs(root, 0);
+}
+
+function dfs(node: TreeNode | null, depth: number): number {
+  if (!node) {
+    return depth;
+  }
+  return Math.max(dfs(node.left, depth + 1), dfs(node.right, depth + 1));
+}
+
+/**
+ * using stack
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function maxDepth(root: TreeNode | null): number {
+  if (!root) {
+    return 0;
+  }
+
+  let max = 0;
+  
+  const stack: [TreeNode | null, number][] = [];
+  stack.push([root, 1]);
+
+  while (stack.length) {
+    const [node, depth] = stack.pop()!;
+
+    if (node) {
+      max = Math.max(max, depth);
+      stack.push([node.left, depth + 1]);
+      stack.push([node.right, depth + 1]);
+    }
+  }
+
+  return max;
+}