递归遍历 | #二叉树的深度#

import java.util.*;
public class Solution {
    public int TreeDepth(TreeNode root) {
        if(root == null)
            return 0;
        int l = TreeDepth(root.left);
        int r = TreeDepth(root.right);
        return Math.max(l, r) + 1;
    }
}

简写

import java.util.*;
public class Solution {
    public int maxDepth (TreeNode root) {
        //空节点没有深度
        if(root == null) 
            return 0;
        //返回子树深度+1
        return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1; 
    }
}