Leetcode[110]-Balanced Binary Tree

Link: https://leetcode.com/problems/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.

推断一棵树是否属于平衡二叉树

推断主节点的左右节点深度大小差，假设不在【-1,1】内。返回false。否则。继续推断其左右节点是否属于平衡二叉树；

仅仅要有不满足的。就返回false

Code(C++):

/**
* 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:
bool isBalanced(TreeNode* root) {
if(root == NULL) return true;

int ldepth = getDepth(root->left);
int rdepth = getDepth(root->right);

if(ldepth - rdepth > 1 || ldepth - rdepth < -1) return false;

return isBalanced(root->left) && isBalanced(root->right);
}

//get node's depth
int getDepth(TreeNode *root){
if(root==NULL) return 0;

int ldepth=0,rdepth=0;
ldepth = getDepth(root->left);
rdepth = getDepth(root->right);

return ldepth > rdepth ? ldepth+1:rdepth+1;

}
};