Create 0094-binary-tree-inorder-traversal.cpp

Author: Ritesh7766

cpp/0094-binary-tree-inorder-traversal.cpp

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+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+#include <stack>
+
+class Solution {
+public:
+    /* Recursive
+    vector<int> helper(TreeNode* node, vector<int>& path) {
+        if (node == NULL)
+            return path;
+
+        path = helper(node->left, path);
+        path.push_back(node->val);
+        path = helper(node->right, path);
+        return path;
+    }
+    */
+
+    // Iterative
+    vector<int> inorderTraversal(TreeNode* root) {
+        stack<TreeNode*> stk;
+        vector<int> path;
+        TreeNode* current = root;
+
+        while (!stk.empty() || current != NULL) {
+            while (current != NULL) {
+                stk.push(current);
+                current = current->left;
+            }
+            TreeNode* node = stk.top();
+            path.push_back(node->val);
+            stk.pop();
+            current = node->right;
+        }
+        return path;
+    }
+};