Merge pull request #55 from kumar007ambi/ambikaDSAMastery

Tree Related Problems

C++/Data-Structures/04-tree/inorder_tree_traversal.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// Definition for a binary tree node.
+struct TreeNode {
+    int val;
+    TreeNode *left;
+    TreeNode *right;
+
+    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+};
+
+// Function to insert a node in a Binary Search Tree (BST)
+TreeNode* insert(TreeNode* root, int val) {
+    if (root == NULL) {
+        return new TreeNode(val);
+    }
+    if (val < root->val) {
+        root->left = insert(root->left, val);
+    } else {
+        root->right = insert(root->right, val);
+    }
+    return root;
+}
+
+// Inorder Traversal of the Binary Tree
+void inorderTraversal(TreeNode* root) {
+    if (root == NULL) {
+        return;
+    }
+    inorderTraversal(root->left);  // Traverse left subtree
+    cout << root->val << " ";      // Visit node
+    inorderTraversal(root->right); // Traverse right subtree
+}
+
+int main() {
+    TreeNode* root = NULL;
+    int n, val;
+    // Taking number of elements as input
+    cout << "Enter the number of nodes: ";
+    cin >> n;
+    // Taking node values as input
+    cout << "Enter the values of the nodes:\n";
+    for (int i = 0; i < n; i++) {
+        cin >> val;
+        root = insert(root, val); // Insert each value in the BST
+    }
+    // Performing inorder traversal
+    cout << "Inorder Traversal: ";
+    inorderTraversal(root);
+    cout << endl;
+    return 0;
+}
+
+// Enter the number of nodes: 5
+// Enter the values of the nodes:
+// 4 2 5 1 3
+// Inorder Traversal: 1 2 3 4 5

C++/Data-Structures/04-tree/postorder_tree_traversal.cpp

@@ -0,0 +1,68 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// Define the structure for the binary tree node
+struct Node {
+    int data;
+    Node* left;
+    Node* right;
+
+    Node(int val) {
+        data = val;
+        left = right = nullptr;
+    }
+};
+
+// Function to insert nodes in the binary tree
+Node* insertNode(Node* root, int data) {
+    if (root == nullptr) {
+        return new Node(data);
+    }
+    if (data < root->data) {
+        root->left = insertNode(root->left, data);
+    } else {
+        root->right = insertNode(root->right, data);
+    }
+    return root;
+}
+
+// Function to perform postorder traversal of the binary tree
+void postorderTraversal(Node* root) {
+    if (root == nullptr) {
+        return;
+    }
+    // Traverse the left subtree
+    postorderTraversal(root->left);
+    // Traverse the right subtree
+    postorderTraversal(root->right);
+    // Visit the root node
+    cout << root->data << " ";
+}
+
+int main() {
+    Node* root = nullptr;
+    int n, value;
+    // Take the number of nodes to be inserted
+    cout << "Enter the number of nodes: ";
+    cin >> n;
+    // Insert nodes into the binary tree
+    for (int i = 0; i < n; i++) {
+        cout << "Enter value of node " << (i + 1) << ": ";
+        cin >> value;
+        root = insertNode(root, value);
+    }
+    // Perform postorder traversal
+    cout << "Postorder Traversal: ";
+    postorderTraversal(root);
+    cout << endl;
+
+    return 0;
+}
+
+// Enter the number of nodes: 5
+// Enter value of node 1: 10
+// Enter value of node 2: 5
+// Enter value of node 3: 20
+// Enter value of node 4: 3
+// Enter value of node 5: 7
+// Postorder Traversal: 3 7 5 20 10

C++/Data-Structures/04-tree/preorder_tree_traversal.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// Definition of a binary tree node
+struct TreeNode {
+    int val;
+    TreeNode* left;
+    TreeNode* right;
+
+    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+};
+
+// Function to perform preorder traversal
+void preorderTraversal(TreeNode* root) {
+    if (root == NULL) return;
+    // Visit the root node
+    cout << root->val << " ";
+    // Traverse the left subtree
+    preorderTraversal(root->left);
+    // Traverse the right subtree
+    preorderTraversal(root->right);
+}
+
+// Function to create a binary tree from user input
+TreeNode* createTree() {
+    int val;
+    cout << "Enter node value (-1 for NULL): ";
+    cin >> val;
+    // Base case for recursion
+    if (val == -1) return NULL;
+    // Create a new node with the given value
+    TreeNode* root = new TreeNode(val);
+    // Recursively create the left and right subtrees
+    cout << "Enter left child of " << val << ": ";
+    root->left = createTree();
+    cout << "Enter right child of " << val << ": ";
+    root->right = createTree();
+    return root;
+}
+
+int main() {
+    // Create the binary tree
+    TreeNode* root = createTree();
+    // Perform preorder traversal
+    cout << "Preorder Traversal: ";
+    preorderTraversal(root);
+    cout << endl;
+    return 0;
+}
+
+// Enter node value (-1 for NULL): 1
+// Enter left child of 1: 2
+// Enter left child of 2: -1
+// Enter right child of 2: -1
+// Enter right child of 1: 3
+// Enter left child of 3: -1
+// Enter right child of 3: -1
+// Preorder Traversal: 1 2 3