Add All Greater Values to Every Node in the Given BST

Here we will see one interesting problem, where we will add greater values to every node in one given binary search tree. So the initial and final tree will be look like below −

Algorithm

bstUpdate(root, sum) −

Begin
   if root is null, then stop
   bstUpdate(right of room, sum)
   sum := sum + value of root
   update root value using sum
   bstUpdate(left of room, sum)
End

Example

#include<iostream>
using namespace std;
class Node {
   public:
      int data;
      Node *left, *right;
   };
   Node *getNode(int item) {
      Node *newNode = new Node();
      newNode->data = item;
      newNode->left = newNode->right = NULL;
      return newNode;
}
void updateBST(Node *root, int *sum) {
   if (root == NULL)
      return;
   updateBST(root->right, sum); //update right sub tree
   *sum = *sum + root->data;
   root->data = *sum; //update root data
   updateBST(root->left, sum); //update left sub tree
}
void BSTUpdate(Node *root) {
   int sum = 0;
   updateBST(root, &sum);
}
void inorder(Node *root) {
   if (root != NULL) {
      inorder(root->left);
      cout<<root->data<<" ";
      inorder(root->right);
   }
}
Node* insert(Node* node, int data) {
   if (node == NULL)
      return getNode(data);
   if (data <= node->data) //go to left
      node->left = insert(node->left, data);
   else //go to right
      node->right = insert(node->right, data);
   return node;
}
int main() {
   int data[] = {50, 30, 20, 40, 70, 60, 80};
   int n = sizeof(data)/sizeof(data[0]);
   Node *root = NULL;
   for(int i = 0; i < n; i++) {
      root = insert(root, data[i]);
   }
   BSTUpdate(root);
   inorder(root);
}

Output

350 330 300 260 210 150 80