Data Structure Binary Tree: Boundary Traversal of binary tree

http://www.geeksforgeeks.org/boundary-traversal-of-binary-tree/

 1 #include <iostream>

 2 #include <vector>

 3 #include <algorithm>

 4 #include <queue>

 5 #include <stack>

 6 #include <string>

 7 #include <fstream>

 8 #include <map>

 9 using namespace std;

10 

11 struct node {

12     int data;

13     struct node *left, *right;

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

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

16 };

17 

18 void printleft(node *root) {

19     if (!root) return;

20     if (root->left) {

21         cout << root->data << " ";

22         printleft(root->left);

23     }

24     else if (root->right) {

25         cout << root->data << " ";

26         printleft(root->right);

27     }

28 }

29 

30 void printleaf(node *root) {

31     if (!root) return;

32     printleaf(root->left);

33     if (!root->left && !root->right) cout << root->data << " ";

34     printleaf(root->right);

35 }

36 

37 void printright(node *root) {

38     if (!root) return;

39     if (root->right) {

40         printright(root->right);

41         cout << root->data << " ";

42     }

43     else if (root->left) {

44         printright(root->left);

45         cout << root->data << " ";

46     }

47 }

48 

49 void printboundary(node *root) {

50     if (!root) return;

51     cout << root->data << " ";

52     printleft(root->left);

53     printleaf(root);

54     printright(root->right);

55 }

56 

57 int main() {

58     node *root = new node(20);

59     root->left = new node(8);

60     root->right = new node(22);

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

62     root->left->right = new node(12);

63     root->right->right = new node(25);

64     root->left->right->left = new node(10);

65     root->left->right->right = new node(14);

66     printboundary(root);

67     return 0;

68 }