Data Structure Binary Tree: How to determine if a binary tree is height-balanced?

http://www.geeksforgeeks.org/how-to-determine-if-a-binary-tree-is-balanced/

 1 #include <iostream>

 2 #include <vector>

 3 #include <algorithm>

 4 #include <queue>

 5 #include <stack>

 6 using namespace std;

 7 

 8 struct node {

 9     int data;

10     struct node *left, *right;

11     node() : data(0), left(NULL), right(NULL) { }

12     node(int d) : data(d), left(NULL), right(NULL) { }

13 };

14 

15 void print(node *node) {

16     if (!node) return;

17     print(node->left);

18     cout << node->data << " ";

19     print(node->right);

20 }

21 

22 bool balanced(node *root, int &height) {

23     if (!root) return true;

24     int l = 0;

25     int r = 0;

26     if (!balanced(root->left, l) || !balanced(root->right, r)) return false;

27     if (l - r >= 2 || r - l >= 2) return false;

28     height = max(l, r) + 1;

29     return true;

30 }

31 

32 

33 int main() {

34     struct node* root = new node(1);

35     root->left = new node(2);

36     root->right = new node(3);

37     root->left->left = new node(4);

38     root->left->right = new node(5);

39     root->right->left = new node(6);

40     root->left->left->left = new node(7);

41     int height = 0;

42     if (balanced(root, height)) cout << "yes" << endl;

43     else cout << "NO" << endl;

44     return 0;

45 }