[LeetCode] Balanced Binary Tree

Question：

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

1、题型分类：

2、思路：

3、时间复杂度：

4、代码：

import java.util.SortedSet;
import java.util.TreeSet;
public class Solution {
    public boolean isBalanced(TreeNode root) {
        if(root==null) return true;
        int leftDepth=depth(root.left);
        int rightDepth=depth(root.right);
        if(Math.abs(leftDepth-rightDepth)>1) return false;
        return isBalanced(root.left)&&isBalanced(root.right);
    }
    public int depth(TreeNode root){  
        if(root==null){  
            return 0;  
        }  
        return 1+Math.max(depth(root.left), depth(root.right));  
    }
}

5、优化：

6、扩展：