Maximum Depth of Binary Tree

PYTHON INTERVIEW/Maximum_Depth_of_Binary_Tree.md

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+# 🧩 Maximum Depth of Binary Tree
+
+## 📘 Problem Statement
+Given the root of a binary tree, return its **maximum depth**.  
+A binary tree's maximum depth is the number of nodes along the **longest path** from the root node down to the farthest leaf node.
+
+
+---
+// Definition for a binary tree node
+class TreeNode {
+    int val;
+    TreeNode left;
+    TreeNode right;
+
+    TreeNode(int val) {
+        this.val = val;
+        this.left = null;
+        this.right = null;
+    }
+}
+
+class Solution {
+    public int maxDepth(TreeNode root) {
+        // Base case: if the tree is empty
+        if (root == null) {
+            return 0;
+        }
+
+        // Recursively find depth of left and right subtrees
+        int leftDepth = maxDepth(root.left);
+        int rightDepth = maxDepth(root.right);
+
+        // Return max depth between left and right, plus 1 for current node
+        return 1 + Math.max(leftDepth, rightDepth);
+    }
+}
+
+
+
+Approach:
+
+    If the current node is None, return 0.
+
+    Recursively compute the depth of the left and right subtrees.
+
+    Add 1 for the current node level.
+
+    Return the maximum of the two subtree depths.
+
+⏱️ Time Complexity
+
+O(n) — Every node is visited once.
+
+💾 Space Complexity
+
+O(h) — Due to recursive call stack, where h is the height of the tree.
+