Title
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.
Example 1:
Given the following tree [3,9,20,null,null,15,7]:
3
/ \
9 20
/ \
15 7 Return true.
Example 2:
Given the following tree [1,2,2,3,3,null,null,4,4]:
1
/ \
2 2
/ \
3 3
/ \
4 4 Return false.
判断是否是一个平衡二叉树
Solution
//cpp:
/**
* 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 depth(TreeNode* t){
if(!t)
return 0;
return max(depth(t->left),depth(t->right))+1;
}
bool isBalanced(TreeNode* root) {
if(!root)
return true;
else{
int l=depth(root->left);
int r=depth(root->right);
return abs(l-r)<=1&&isBalanced(root->left)&&isBalanced(root->right);
}
}
};