LeetCode 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.

Example 1:

Given the following tree [3,9,20,null,null,15,7]:

Return true.

Example 2:

Given the following tree [1,2,2,3,3,null,null,4,4]:

Return false.

 

判断是否为平衡二叉树

c++

class Solution {
public:
    bool isBalanced(TreeNode* root) {
        if(root == NULL) return true;
        bool tagleft=true;bool tagright=true;
        int dleft=0;int dright=0;
        if(root->left!=NULL)
            tagleft = isBalanced(root->left);
        if(root->right!=NULL)
            tagright = isBalanced(root->right);
        
        if(root->left!=NULL)
            dleft = deep(root->left);
        if(root->right!=NULL)
            dright = deep(root->right);
        
        if(tagleft&&tagright&&abs(dleft-dright)<=1)
            return true;
        else
            return false;
        
    }
    
    int deep(TreeNode* root)
    {
        
        int dleft=0;int dright=0;
        if(root->left!=NULL)
            dleft = deep(root->left);
        if(root->right!=NULL)
            dright = deep(root->right);
        
        return max(dleft,dright)+1;
    }
};