Create main.cpp

Author: JawadSher

19 - Heap Data Structure Problems/08 - Convert BST to Min Heap/main.cpp

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+#include <iostream>
+#include <vector>
+using namespace std;
+
+// Definition for a Node in the Binary Tree
+class Node {
+public:
+    int data;
+    Node* left;
+    Node* right;
+  
+    // Constructor to create a new node with given value
+    Node(int val) {
+        this->data = val;
+        this->left = NULL;
+        this->right = NULL;
+    }
+};
+
+// Function to perform inorder traversal on the BST
+// This collects all node values in sorted order
+void inOrder(Node* root, vector<int>& nodes) {
+    if (root == NULL) return; // Base case for recursion
+
+    inOrder(root->left, nodes);      // Traverse left subtree
+    nodes.push_back(root->data);     // Visit node and add its value to the vector
+    inOrder(root->right, nodes);     // Traverse right subtree
+}
+
+// Function to transform the BST to a Min Heap using preorder traversal
+// It assigns values from the sorted list to each node
+void inOrderToMinHeap(Node* root, vector<int>& nodes, int& index) {
+    if (root == NULL) return; // Base case for recursion
+
+    // Assign the current node with the next value in sorted order
+    root->data = nodes[index++];
+
+    // Continue assigning values to left and right children
+    inOrderToMinHeap(root->left, nodes, index);
+    inOrderToMinHeap(root->right, nodes, index);
+}
+
+// Main function to convert BST to Min Heap
+void BST_to_MinHeap(Node* root) {
+    if (root == NULL) { // Check for an empty tree
+        cout << "Empty Tree" << endl;
+        return;
+    }
+
+    vector<int> nodes; // Vector to store nodes in sorted order
+
+    // Step 1: Store elements of BST in sorted order
+    inOrder(root, nodes);
+
+    int index = 0;
+    // Step 2: Assign values from sorted list to nodes in preorder traversal
+    inOrderToMinHeap(root, nodes, index);
+}
+
+// Function to print the tree in preorder to check Min Heap property
+void print(Node* root) {
+    if (root == NULL) return; // Base case for recursion
+
+    cout << root->data << " "; // Print current node
+    print(root->left);         // Print left subtree
+    print(root->right);        // Print right subtree
+}
+
+int main() {
+    // Constructing a simple BST
+    Node* root = new Node(4);
+    root->left = new Node(2);
+    root->right = new Node(6);
+    root->left->left = new Node(1);
+    root->left->right = new Node(3);
+    root->right->left = new Node(5);
+    root->right->right = new Node(7);
+
+    // Convert BST to Min Heap
+    BST_to_MinHeap(root);
+    
+    // Print the tree in preorder to verify Min Heap property
+    cout << "Preorder of Min Heap : ";
+    print(root);
+    cout << endl;
+    
+    return 0;
+}