BalancedBinaryTree.cpp

#include<iostream>
#include <bits/stdc++.h>
using namespace std;


//   Definition for a binary tree node.
  struct TreeNode {
      int val;
      TreeNode *left;
      TreeNode *right;
      TreeNode() : val(0), left(nullptr), right(nullptr) {}
      TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
      TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
  };
 
class Solution {
private:
    int dfs(TreeNode* root){
        if(!root) return 0;
        
        int l=dfs(root->left);
        if(l==-1) return -1;
        int r=dfs(root->right);
        if(r==-1) return -1;
        
        if(abs(l-r)>1) return -1;
        
        return 1+max(l,r);
    }
public:
    bool isBalanced(TreeNode* root) {
        return dfs(root)!=-1;
    }
};