题解 | #二叉树的最大深度#

1. 递归

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    public int maxDepth (TreeNode root) {
        if(root == null){
            return 0;
        }
        return maxDeep(root);
    }
    public static int maxDeep(TreeNode root){
        if(root == null){
            return 0;
        }
        return Math.max(maxDeep(root.left),maxDeep(root.right))+1;
    }
}