Balanced Binary Tree

 1    int height( TreeNode * root )
 2     {
 3         if ( root == NULL )
 4             return 0;
 5         else
 6             return max( height( root->left ), height( root->right) ) + 1;
 7     }
 8     
 9     bool isBalanced(TreeNode* root) {
10        if ( root == NULL )
11         return true;
12         
13         if ( abs(height(root->left)-height(root->right)) > 1 )
14             return false;
15         else
16             return isBalanced( root->left ) && isBalanced( root->right );
17     }