Balanced Binary Tree @LeetCode

PROBLEM :

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.

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SIMPLE c++ IMPLEMENTATION :( O(n^2) Solution )
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 /*
 * 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 l=height(root->left) ;
        int r=height(root->right) ;
     
        if(abs(l-r)<2&&(isBalanced(root->left)&&isBalanced(root->right)))
            return true ;
        return false ;
    }
 
    int height(TreeNode* root){
        if(root==NULL)
            return 0 ;
         
        int l=height(root->left) ;
        int r=height(root->right) ;
     
        return l>r?l+1:r+1 ;
    }
};

--------------------------------------------------------------------------------
SIMPLE c++ IMPLEMENTATION :( O(n) Solution )
--------------------------------------------------------------------------------

/**
 * 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(CheckBalenced(root)==-1)
            return false ;
        return true ;
    }
 
    int CheckBalenced(TreeNode* root){
        if(root==NULL)
            return 0 ;
         
        int l=CheckBalenced(root->left) ;
        if(l==-1)
            return -1 ;
         
        int r=CheckBalenced(root->right) ;
        if(r==-1)
            return -1 ;
         
        if(abs(l-r)>1)
            return -1 ;
         
        return l>r?l+1:r+1 ;
    }
};

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