Create main.cpp

Author: JawadSher

17 - Binary Tree Data Structure Problems/01 - Example/main.cpp

@@ -0,0 +1,199 @@
+#include <iostream>
+using namespace std;
+#include <queue>
+#include <stack>
+
+class Node{
+    public:
+        int data;
+        Node* left;
+        Node* right;
+        
+    Node(int data){
+        this -> data = data;
+        this -> left = NULL;
+        this -> right = NULL;
+    }
+};
+
+Node* buildTree(Node* root){
+    cout << "Enter the data : " << endl;
+    int data;
+    cin >> data;
+    root = new Node(data);
+    
+    if(data == -1) return NULL;
+    
+    cout << "Enter data for inserting in the left of " << data << endl;
+    root->left = buildTree(root->left);
+    
+    cout << "Enter data for inserting in the right of "<< data << endl;
+    root->right = buildTree(root->right);
+    
+    return root;
+}
+
+void levelOrderTraversal(Node* root){
+    queue<Node*> q;
+    q.push(root);
+    q.push(NULL); // Separator
+    
+    while(!q.empty()){
+        Node* temp = q.front();
+        q.pop();
+        
+        if(temp == NULL){
+            // previous level completed
+            cout << endl;
+            if(!q.empty()){
+                // Queue has still some child nodes
+                q.push(NULL);
+            }
+        }else{
+            cout << temp -> data << " ";
+            if(temp -> left) q.push(temp -> left);
+            if(temp -> right) q.push(temp -> right);
+        }
+    }
+}
+
+void reverseLevelOrderTraversal(Node* root) {
+    if (root == NULL) return;
+
+    queue<Node*> q;
+    stack<Node*> st;
+
+    // Push the root to the queue and a NULL to mark the end of the level
+    q.push(root);
+    q.push(NULL); // NULL acts as a level separator
+
+    while (!q.empty()) {
+        Node* temp = q.front();
+        q.pop();
+
+        if (temp == NULL) {
+            // End of current level
+            st.push(NULL); // Push NULL to the stack to mark level boundary
+
+            if (!q.empty()) {
+                q.push(NULL); // Add separator for the next level
+            }
+        } else {
+            // Push the node data into the stack
+            st.push(temp);
+
+            // Enqueue right child first, then left child to maintain reverse level order
+            if (temp->right) q.push(temp->right);
+            if (temp->left) q.push(temp->left);
+        }
+    }
+
+    // Print nodes from the stack in reverse level order with levels separated
+    while (!st.empty()) {
+        Node* node = st.top();
+        st.pop();
+
+        if (node == NULL) {
+            cout << endl; // Newline after each level
+        } else {
+            cout << node->data << " ";
+        }
+    }
+    cout << endl;
+}
+
+void inOrderTraversal(Node* root){
+    if(root == NULL) return;
+    
+    inOrderTraversal(root->left);
+    cout<< root -> data << " ";
+    inOrderTraversal(root->right);
+}
+
+void preOrderTraversal(Node* root){
+    if(root == NULL) return;
+    
+    cout<< root -> data << " ";
+    preOrderTraversal(root->left);
+    preOrderTraversal(root->right);
+}
+
+void postOrderTraversal(Node* root){
+    if(root == NULL) return;
+    
+    postOrderTraversal(root->left);
+    postOrderTraversal(root->right);
+    cout << root -> data << " ";
+}
+
+void buildFromLevelOrder(Node* &root){
+    queue<Node *> q;
+    cout << "Enter data for root " << endl;
+    int data;
+    cin >> data ;
+    root = new Node(data);
+    q.push(root);
+    
+    while(!q.empty()){
+        Node* temp = q.front();
+        q.pop();
+        
+        cout << "Enter left Node for : " << temp -> data <<endl;
+        int leftData;
+        cin>> leftData;
+        
+        if(leftData != -1){
+            temp -> left = new Node(leftData);
+            q.push(temp->left);
+        }
+        
+        cout << "Enter right Node for : " << root -> data <<endl;
+        int rightData;
+        cin>> rightData;
+        
+        if(rightData != -1){
+            temp -> right = new Node(rightData);
+            q.push(temp->right);
+        }
+    }
+}
+
+int main() {
+    Node* root = NULL;
+    
+    // Creating buildTree
+    root = buildTree(root);
+    
+    // // data : 1 3 7 -1 -1 11 -1 -1 5 17 -1 -1 -1
+    
+    // // level order Traversal
+    // cout << "Printing the level order traversal output " <<endl;
+    // levelOrderTraversal(root);
+    
+    // Reverse Level Order Traversal
+    cout << "Printing the reverse order traversal output " << endl;
+    reverseLevelOrderTraversal(root);
+    
+    // cout << "Inorder Taversal is : ";
+    // inOrderTraversal(root);
+    
+    // cout << endl;
+    
+    // cout << "Preorder Traversal is : ";
+    // preOrderTraversal(root);
+    
+    // cout << endl;
+    
+    // cout << "Postorder Traversal is : ";
+    // postOrderTraversal(root);
+    
+    // 1 3 5 7 11 17 -1 -1 -1 -1 -1 -1 -1
+    // Create from level order
+    // buildFromLevelOrder(root);
+    
+    // // // level order
+    // cout << "Printing the level order traversal output " <<endl;
+    // levelOrderTraversal(root);
+
+    return 0;
+}