Data Structure Binary Tree: Level order traversal in spiral form

http://www.geeksforgeeks.org/level-order-traversal-in-spiral-form/

 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 void printspiral(node* root) {

23     if (!root) return;

24     bool flag = true;

25     stack<node*> S, T;

26     S.push(root);

27     while (!S.empty()) {

28         while (!S.empty()) {

29             node *top = S.top();

30             S.pop();

31             cout << top->data << " ";

32             if (!flag) {

33                 if (top->left) T.push(top->left);

34                 if (top->right) T.push(top->right);

35             }

36             else {

37                 if (top->right) T.push(top->right);

38                 if (top->left) T.push(top->left);

39             }

40         }

41         swap(S, T);

42         flag = !flag;

43     }

44 }

45 

46 

47 int main() {

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

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

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

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

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

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

54     root->right->right = new node(4);

55     printspiral(root);

56     return 0;

57 }