# Maximum Depth of Binary Tree

{% embed url="<https://leetcode.com/problems/maximum-depth-of-binary-tree/>" %}

{% embed url="<https://www.lintcode.com/problem/97/>" %}

## Solution 1 (Golang)

```go
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func maxDepth(root *TreeNode) int {
    if root == nil {
        return 0
    }
    return max(maxDepth(root.Left), maxDepth(root.Right)) + 1
}

func max(x, y int) int {
    if x > y {
        return x
    }
    return y
}
```

## Solution 2 (Java)

```java
/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */

public class Solution {
    /**
     * @param root: The root of binary tree.
     * @return: An integer
     */
    public int maxDepth(TreeNode root) {
        if (root == null) return 0;
        return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
    }
}
```

### Notes

* &#x20;Recursion with divide and conquer

## Solution 3 (Java)

```java
/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */

public class Solution {

    int maxDepth = 0;
    /**
     * @param root: The root of binary tree.
     * @return: An integer
     */
    public int maxDepth(TreeNode root) {
        maxDepthHelper(root, 1);
        return maxDepth;
    }

    private void maxDepthHelper(TreeNode root, int depth) {
        if (root == null) return;
        if (depth > maxDepth) maxDepth = depth;
        
        maxDepthHelper(root.left, depth + 1);
        maxDepthHelper(root.right, depth + 1);
    }
}
```

### Notes

* &#x20;Recursion with traversal


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://blog.yushunchen.com/algo/binary-tree/2.-classical-questions/maximum-depth-of-binary-tree.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.