/**
* This function merges two balanced BSTs with roots as root1 and root2.
* m and n are the sizes of the trees respectively
*/
struct node* mergeTrees(struct node *root1, struct node *root2, int m, int n)
{
/**
* Store inorder traversal of first tree in an array arr1[]
*/
int *arr1 = new int[m];
int i = 0;
storeInorder(root1, arr1, &i);
/**
* Store inorder traversal of second tree in another array arr2[]
*/
int *arr2 = new int[n];
int j = 0;
storeInorder(root2, arr2, &j);
/**
* Merge the two sorted array into one
*/
int *mergedArr = merge(arr1, arr2, m, n);
/**
* Construct a tree from the merged array and return root of the tree
*/
return sortedArrayToBST(mergedArr, 0, m+n-1);
}
/**
* A helper function that stores inorder traversal of a tree in inorder array
*/
void storeInorder(struct node* node, int inorder[], int *index_ptr)
{
if (node == NULL)
return ;
storeInorder(node->left, inorder, index_ptr);
inorder[*index_ptr] = node->data;
(*index_ptr)++;
storeInorder(node->right, inorder, index_ptr);
}
/* A helper function that stores inorder traversal of a tree rooted with node */
void storeInorder (struct node* node, int inorder[], int *index_ptr)
{
// Base Case
if (node == NULL)
return;
/* first store the left subtree */
storeInorder (node->left, inorder, index_ptr);
/* Copy the root's data */
inorder[*index_ptr] = node->data;
(*index_ptr)++; // increase index for next entry
/* finally store the right subtree */
storeInorder (node->right, inorder, index_ptr);
}
// This function converts a given Binary Tree to BST
void binaryTreeToBST (struct node *root)
{
// base case: tree is empty
if(root == NULL)
return;
/* Count the number of nodes in Binary Tree so that
we know the size of temporary array to be created */
int n = countNodes (root);
// Create a temp array arr[] and store inorder traversal of tree in arr[]
int *arr = new int[n];
int i = 0;
storeInorder (root, arr, &i);
// Sort the array using library function for quick sort
qsort (arr, n, sizeof(arr[0]), compare);
// Copy array elements back to Binary Tree
i = 0;
arrayToBST (arr, root, &i);
// delete dynamically allocated memory to avoid meory leak
delete [] arr;
}
