struct node* constructTreeUtil(int arr[], int* preIndex, int key, int min, int max, int size){
if(*preIndex >= size)return NULL;
struct node* root = NULL;
if(key >min && key < max)
{
root = newNode(key);
*preIndex = *preIndex + 1;
if(*preIndex < size)
{
root->left = constructTreeUtil( arr, preIndex, arr[*preIndex],
min, key, size );
root->right = constructTreeUtil( arr, preIndex, arr[*preIndex],
key, max, size );
}
}
//printf(*preIndex);
return root;
}
// A recursive function to construct Full from pre[] and post[].
// preIndex is used to keep track of index in pre[].
// l is low index and h is high index for the current subarray in post[]
struct node* constructTreeUtil (int pre[], int post[], int* preIndex,
int l, int h, int size)
{
// Base case
if (*preIndex >= size || l > h)
return NULL;
// The first node in preorder traversal is root. So take the node at
// preIndex from preorder and make it root, and increment preIndex
struct node* root = newNode ( pre[*preIndex] );
++*preIndex;
// If the current subarry has only one element, no need to recur
if (l == h)
return root;
// Search the next element of pre[] in post[]
int i;
for (i = l; i <= h; ++i)
if (pre[*preIndex] == post[i])
break;
// Use the index of element found in postorder to divide postorder array in
// two parts. Left subtree and right subtree
if (i <= h)
{
root->left = constructTreeUtil (pre, post, preIndex, l, i, size);
root->right = constructTreeUtil (pre, post, preIndex, i + 1, h, size);
}
return root;
}
struct node* constructTree(int* arr, int size){
int preIndex = 0;
return constructTreeUtil(arr,&preIndex,arr[0], INT_MIN,INT_MAX,size);
}
// The main function to construct Full Binary Tree from given preorder and
// postorder traversals. This function mainly uses constructTreeUtil()
struct node *constructTree (int pre[], int post[], int size)
{
int preIndex = 0;
return constructTreeUtil (pre, post, &preIndex, 0, size - 1, size);
}
