- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Find all the pairs with given sum in a BST in C++
In this tutorial, we are going to write a program that finds all the pairs whose sum is equal to the given number in the binary search tree.
We are going to store and values of trees in two different lists to find the pairs. Let's see the steps to solve the problem.
Create a struct node for a binary tree.
Write a function to insert a new node into the binary search tree.
Remember, in the binary search tree all the elements that are less than root are smaller, and right are larger.
Initialize two empty lists to store the left and right nodes of the tree.
Iterate over the binary search tree until left or right nodes are NULL or both the lists are not empty.
Write a loop to store all the elements into the left nodes list.
Write a loop to store all the elements into the right nodes list.
Get the last nodes from each list.
Check the two values.
If the left side node value is greater than or equal to the right side node value, then break the loop.
If the two values sum is equal to the given number, then print and delete them from the lists
If the two values sum is less than the given number, then delete the last node from the left list and move to the right of the node.
If the two values sum is greater than the given number, then delete the last node from the right list and move to the left of the node.
Example
Let's see the code.
#include<bits/stdc++.h>
using namespace std;
struct Node{
int data;
Node *left, *right, *root;
Node(int data) {
this->data = data;
left = NULL;
right = NULL;
root = NULL;
}
};
Node* insertNewNode(Node *root, int data){
if (root == NULL) {
root = new Node(data);
return root;
}
if (root->data < data) {
root->right = insertNewNode(root->right, data);
}
else if (root->data > data) {
root->left = insertNewNode(root->left, data);
}
return root;
}
void findThePairs(Node *node, int target) {
vector<Node*> left_side_nodes;
vector<Node*> right_side_nodes;
Node *current_left = node;
Node *current_right = node;
while (current_left != NULL || current_right != NULL || (left_side_nodes.size() > 0 && right_side_nodes.size() > 0)) {
while (current_left != NULL) {
left_side_nodes.push_back(current_left);
current_left = current_left->left;
}
while (current_right != NULL) {
right_side_nodes.push_back(current_right);
current_right = current_right->right;
}
Node *left_side_node = left_side_nodes[left_side_nodes.size() - 1];
Node *right_side_node = right_side_nodes[right_side_nodes.size() - 1];
int left_side_value = left_side_node->data;
int right_side_value = right_side_node->data;
if (left_side_value >= right_side_value) {
break;
}
if (left_side_value + right_side_value < target) {
left_side_nodes.pop_back();
current_left = left_side_node->right;
}
else if (left_side_value + right_side_value > target) {
right_side_nodes.pop_back();
current_right = right_side_node->left;
}
else {
cout << left_side_node->data << " " << right_side_node->data << endl;
right_side_nodes.pop_back();
left_side_nodes.pop_back();
current_left = left_side_node->right;
current_right = right_side_node->left;
}
}
}
int main() {
Node *root = NULL;
root = insertNewNode(root, 25);
root = insertNewNode(root, 20);
root = insertNewNode(root, 30);
root = insertNewNode(root, 15);
root = insertNewNode(root, 21);
root = insertNewNode(root, 19);
root = insertNewNode(root, 31);
findThePairs(root, 50);
}t, *root;
Node(int data) {
this->data = data;
left = NULL;
right = NULL;
root = NULL;
}
};
Node* insertNewNode(Node *root, int data){
if (root == NULL) {
root = new Node(data);
return root;
}
if (root->data < data) {
root->right = insertNewNode(root->right, data);
}
else if (root->data > data) {
root->left = insertNewNode(root->left, data);
}
return root;
}
void findThePairs(Node *node, int tar) {
vector<Node*> left_side_nodes;
vector<Node*> right_side_nodes;
Node *current_left = node;
Node *current_right = node;
while (current_left != NULL || current_right != NULL || (left_side_nodes.size() > 0 && right_side_nodes.size() > 0)) {
while (current_left != NULL) {
left_side_nodes.push_back(current_left);
current_left = current_left->left;
}
while (current_right != NULL) {
right_side_nodes.push_back(current_right);
current_right = current_right->right;
}
Node *left_side_node = left_side_nodes[left_side_nodes.size() - 1];
Node *right_side_node = right_side_nodes[right_side_nodes.size() - 1];
int left_side_value = left_side_node->data;
int right_side_value = right_side_node->data;
if (left_side_value >= right_side_value) {
break;
}
if (left_side_value + right_side_value < tar) {
left_side_nodes.pop_back();
current_left = left_side_node->right;
}
else if (left_side_value + right_side_value > tar) {
right_side_nodes.pop_back();
current_right = right_side_node->left;
}
else {
cout << left_side_node->data << " " << right_side_node->data << endl;
right_side_nodes.pop_back();
left_side_nodes.pop_back();
current_left = left_side_node->right;
current_right = right_side_node->left;
}
}
}
int main() {
Node *root = NULL;
root = insertNewNode(root, 25);
root = insertNewNode(root, 20);
root = insertNewNode(root, 30);
root = insertNewNode(root, 15);
root = insertNewNode(root, 21);
root = insertNewNode(root, 19);
root = insertNewNode(root, 31);
findThePairs(root, 50);
}Output
If you run the above code, then you will get the following result.
19 31 20 30
Conclusion
If you have any queries in the tutorial, mention them in the comment section.
- Related Questions & Answers
- Find a pair with given sum in BST in C++
- Print all pairs with given sum in C++
- Find a pair with given sum in a Balanced BST in C++
- Find a pair with given sum in a Balanced BST in Java
- Find a pair with given sum in a Balanced BST in Python
- Count pairs with given sum in C++
- Find pairs with given sum in doubly linked list in C++
- Count all pairs with given XOR in C++
- Find all triplets in a list with given sum in Python
- Check if a triplet with given sum exists in BST in Python
- Print all triplets with given sum in C++
- Find Sum of all unique subarray sum for a given array in C++
- Find sub-matrix with the given sum in C++
- Find all pairs that sum to a target value in JavaScript
- Write a Golang program to find pairs with the given sum in an array(O(n2))