/**
* 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)
/**
* 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
Recursion with divide and conquer
Solution 3 (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);
}
}
