Data Structure Binary Tree: Construct Tree from given Inorder and Preorder traversals

http://www.geeksforgeeks.org/construct-tree-from-given-inorder-and-preorder-traversal/

 1 #include <iostream>

 2 #include <vector>

 3 #include <algorithm>

 4 #include <queue>

 5 #include <stack>

 6 #include <string>

 7 #include <fstream>

 8 using namespace std;

 9 

10 struct node {

11     char data;

12     struct node *left, *right;

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

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

15 };

16 

17 

18 void prints(node *root) {

19     if (!root) return;

20     prints(root->left);

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

22     prints(root->right);

23 }

24 

25 node *buildtree(char in[], char pre[], int beg, int end) {

26     static int preindex = 0;

27     if (beg > end) return NULL;

28     node *root = new node(pre[preindex++]);

29     int index = beg;

30     for (int i = beg; i <= end; i++) {

31         if (in[i] == root->data) {

32             index = i;

33             break;

34         }

35     }

36     root->left = buildtree(in, pre, beg, index-1);

37     root->right = buildtree(in, pre, index+1, end);

38     return root;

39 }

40 

41 int main() {

42     char in[6] = {'D', 'B', 'E', 'A', 'F', 'C'};

43     char pre[6] = {'A', 'B', 'D', 'E', 'C', 'F'};

44     int len = 6;

45     node *root = buildtree(in, pre, 0, len-1);

46     prints(root);

47     return 0;

48 }