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