LeetCode 110. Balanced Binary Tree 题解

题目描述：

110. Balanced Binary Tree

 

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.

解题思路：

本题即判断一棵树是否为平衡二叉树。即对于每一个结点，其左子树的高度与右子树的高度绝对值差不超过1。所以对每个结点来说，首先判断它左右子树是否满足条件，然后判断其左右子节点是否满足条件。使用递归函数可以简单的快速的解决本题。

代码展示：

/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int getHeight(TreeNode * root)
{

if(root==NULL)
return 0;
if(root->left==NULL)
return getHeight(root->right)+1;
if(root->right==NULL)
return getHeight(root->left)+1;
else
{
return max(getHeight(root->left),getHeight(root->right))+1;
}
}
bool isBalanced(TreeNode* root) {
if(root==NULL)
return true;
if(abs(getHeight(root->left)-getHeight(root->right))>=2)
return false;
return isBalanced(root->left)&&isBalanced(root->right);

}
};