题目:
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.
思路:
- 题目的大意是【判断一个二叉树是不是平衡二叉树
- 首先了解平衡二叉树的概念:只有根节点是,或者左右节点的深度只差不大于1
- 因为二叉树本身是一个递归的结构,所以二叉树的好多问题使可以用递归解决的,考虑root和root.left以及root.right的关系
代码:
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */
public class Solution {
public boolean isBalanced(TreeNode root) {
if(root == null){
return true;
}
if(Math.abs(depth(root.left)-depth(root.right)) > 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));
}
}