Maximum Depth of Binary Tree

Maximum Depth of Binary Tree

问题：

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node

思路：

递归

我的方法：

public class Solution {
    public int maxDepth(TreeNode root) {
        if(root == null)
            return 0 ;
        if(root.left == null && root.right == null)
            return 1 ;
        else
        {
            int left = maxDepth(root.left) ;
            int right = maxDepth(root.right) ;
            return Math.max(left , right) + 1 ;
        }
    }
}

别人方法：

public class Solution {
    public int maxDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }

        int left = maxDepth(root.left);
        int right = maxDepth(root.right);
        return Math.max(left, right) + 1;
    }
}

学习之处：

冗余判断了 root.left == null && root.right == null 没有必要进行判断

 

if(root==null) return 0;
return 1 + Math.max(maxDepth(root.left),maxDepth(root.right));