class Solution {
public:
    bool IsBanlanced(TreeNode* pRoot,int* pDepth){
        if(pRoot==NULL){
            *pDepth=0;
            return true;
        }
        int nleft,nright;
        if(IsBanlanced(pRoot->left,&nleft) && 
        IsBanlanced(pRoot->right,&nright)){
            int diff=nleft-nright;
            if(diff<=1 && diff>=-1){
                *pDepth=1+(nleft>nright?nleft:nright);
                return true;
            }
        }

        return false;
    }

    bool IsBalanced_Solution(TreeNode* pRoot) {
        int depth=0;
        return IsBanlanced(pRoot,&depth);
    }
};