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.

使用一個函數紀錄左右子樹的高度以及是否平衡

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int max,min;
    bool subDepth(TreeNode* p,int& d){
        if(!p) return true;
        int l=d+1,r=d+1;
        bool result=subDepth(p->left,l)&&subDepth(p->right,r)&&(abs(l-r)<=1);
        d=l>r?l:r;
        return result;
    }
   
    bool isBalanced(TreeNode *root) {
        int depth=0;
        return subDepth(root,depth);
    }
};