update inorder traversal

Author: akgmage

Trees/Binary Trees/inorder_traversal.cpp

@@ -13,42 +13,71 @@
  Input : 40 10 5 1 -1 -1 -1 -1 30 -1 28 15 -1 -1 20 -1 -1
  Output : 1->5->10->40->30->15->28->20  
 */
-#include<bits/stdc++.h>
-using namespace std;
-class Node{
-    public:
-        int data;
-        Node* left;
-        Node* right;
-
-        Node(int x){
-            data = x;
-            left = NULL;
-            right = NULL;
-        }
+#include <iostream>
+#include <vector>
+#include <stack>
+
+// Definition for a binary tree node.
+struct TreeNode {
+    int val;
+    TreeNode* left;
+    TreeNode* right;
+    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 };
-Node* build_binary_tree(){
-    int data;
-    cin >> data;
-    if(data == -1){
-        return NULL;
+
+class Solution {
+public:
+    std::vector<int> inorderTraversal(TreeNode* root) {
+        // Vector to store the in-order traversal result
+        std::vector<int> result;
+
+        // Stack to simulate the recursive call stack
+        std::stack<TreeNode*> stack;
+
+        // Current node starts from the root
+        TreeNode* current = root;
+
+        // Continue traversal until the current node is null and the stack is empty
+        while (current != nullptr || !stack.empty()) {
+            // Traverse all the way to the leftmost node, pushing each node onto the stack
+            while (current != nullptr) {
+                stack.push(current);
+                current = current->left;
+            }
+
+            // Pop the top node from the stack (current leftmost node)
+            current = stack.top();
+            stack.pop();
+
+            // Add the value of the current node to the result vector
+            result.push_back(current->val);
+
+            // Move to the right subtree of the current node
+            current = current->right;
+        }
+
+        // Return the final in-order traversal result
+        return result;
     }
-    Node* root = new Node(data);
-    root->left = build_binary_tree();
-    root->right = build_binary_tree();
-    return root;
-}
-void print_binary_tree(Node* root){
-    if(root == NULL){
-        return;
+};
+
+// Example usage
+int main() {
+    // Create a sample binary tree
+    TreeNode* root = new TreeNode(1);
+    root->right = new TreeNode(2);
+    root->right->left = new TreeNode(3);
+
+    // Perform in-order traversal
+    Solution solution;
+    std::vector<int> result = solution.inorderTraversal(root);
+
+    // Print the result
+    for (int val : result) {
+        std::cout << val << " ";
     }
-    print_binary_tree(root->left);
-    cout << root->data << "->";
-    print_binary_tree(root->right);
-}
-int main(){
-    Node* root = build_binary_tree();
-    print_binary_tree(root);
-    return 0;    
+
+    // Output: 1 3 2
+    return 0;
 }