#144. Binary Preorder Traversal

.vscode/c_cpp_properties.json

@@ -0,0 +1,18 @@
+{
+  "configurations": [
+    {
+      "name": "macos-clang-arm64",
+      "includePath": [
+        "${workspaceFolder}/**"
+      ],
+      "compilerPath": "/usr/bin/clang",
+      "cStandard": "${default}",
+      "cppStandard": "${default}",
+      "intelliSenseMode": "macos-clang-arm64",
+      "compilerArgs": [
+        ""
+      ]
+    }
+  ],
+  "version": 4
+}

.vscode/launch.json

@@ -0,0 +1,7 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": []
+}

.vscode/settings.json

@@ -0,0 +1,62 @@
+{
+  "C_Cpp_Runner.cCompilerPath": "clang",
+  "C_Cpp_Runner.cppCompilerPath": "clang++",
+  "C_Cpp_Runner.debuggerPath": "lldb",
+  "C_Cpp_Runner.cStandard": "",
+  "C_Cpp_Runner.cppStandard": "",
+  "C_Cpp_Runner.msvcBatchPath": "",
+  "C_Cpp_Runner.useMsvc": false,
+  "C_Cpp_Runner.warnings": [
+    "-Wall",
+    "-Wextra",
+    "-Wpedantic",
+    "-Wshadow",
+    "-Wformat=2",
+    "-Wcast-align",
+    "-Wconversion",
+    "-Wsign-conversion",
+    "-Wnull-dereference"
+  ],
+  "C_Cpp_Runner.msvcWarnings": [
+    "/W4",
+    "/permissive-",
+    "/w14242",
+    "/w14287",
+    "/w14296",
+    "/w14311",
+    "/w14826",
+    "/w44062",
+    "/w44242",
+    "/w14905",
+    "/w14906",
+    "/w14263",
+    "/w44265",
+    "/w14928"
+  ],
+  "C_Cpp_Runner.enableWarnings": true,
+  "C_Cpp_Runner.warningsAsError": false,
+  "C_Cpp_Runner.compilerArgs": [],
+  "C_Cpp_Runner.linkerArgs": [],
+  "C_Cpp_Runner.includePaths": [],
+  "C_Cpp_Runner.includeSearch": [
+    "*",
+    "**/*"
+  ],
+  "C_Cpp_Runner.excludeSearch": [
+    "**/build",
+    "**/build/**",
+    "**/.*",
+    "**/.*/**",
+    "**/.vscode",
+    "**/.vscode/**"
+  ],
+  "C_Cpp_Runner.useAddressSanitizer": false,
+  "C_Cpp_Runner.useUndefinedSanitizer": false,
+  "C_Cpp_Runner.useLeakSanitizer": false,
+  "C_Cpp_Runner.showCompilationTime": false,
+  "C_Cpp_Runner.useLinkTimeOptimization": false,
+  "C_Cpp_Runner.msvcSecureNoWarnings": false,
+  "files.associations": {
+    "__locale": "cpp"
+  }
+}

.vscode/tasks.json

@@ -0,0 +1,29 @@
+{
+    "tasks": [
+        {
+            "type": "cppbuild",
+            "label": "C/C++: clang build active file",
+            "command": "/usr/bin/clang",
+            "args": [
+                "-fcolor-diagnostics",
+                "-fansi-escape-codes",
+                "-g",
+                "${file}",
+                "-o",
+                "${fileDirname}/${fileBasenameNoExtension}"
+            ],
+            "options": {
+                "cwd": "${fileDirname}"
+            },
+            "problemMatcher": [
+                "$gcc"
+            ],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
+            "detail": "Task generated by Debugger."
+        }
+    ],
+    "version": "2.0.0"
+}

C++/Binary-Tree-Preorder-Traversal.cpp

@@ -0,0 +1,43 @@
+/**
+ * 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) {}
+ * };
+ */
+//This solution is an interative solution for problem #144 using stack
+//Preorder Traversal is root, left, right
+//The Space and Time Complexity is O(n)
+class Solution {
+public:
+    vector<int> preorderTraversal(TreeNode* root) {
+        vector<int> result;
+
+        //if root == nullptr, return empty vector
+        if (root == NULL) {
+            return result;
+        }
+
+        stack<TreeNode*> node_stack;
+        node_stack.push(root);
+
+        while (!node_stack.empty()) {
+            TreeNode* node = node_stack.top(); 
+            node_stack.pop(); //pop the top node from the stack
+            result.push_back(node->val); //add the value to the result vector
+
+            if (node->right) {
+                node_stack.push(node->right); //push right child to the stack if it exists
+            }
+            if (node->left) {
+                node_stack.push(node->left); //push left child to the stack if it exists
+            }
+        }
+
+        return result;
+    }
+};

README.md

@@ -248,7 +248,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 094  | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)                   | [Java](./Java/binary-tree-inorder-traversal.java) <br> [Python](./Python/Iterative-Inorder-tree-traversal)       | _O(n)_      | _O(logn)_   | Medium     | Binary Tree, Stack, HashTable                  |      |
 | 100  | [Same Tree](https://leetcode.com/problems/same-tree/)                                                           | [Python](./Python/100.SymmetricTree.py)<br>[Java](./Java/Same-Tree.java)                                         | _O(n)_      | _O(n)_      | Easy       | Tree, Depth-first Search                       |      |
 | 101  | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)                                                 | [Java](./Java/symmetric-tree.java)<br>[Python](./Python/101.SymmetricTree.py)                                    | _O(n)_      | _O(n)_      | Easy       | Tree, Breadth-first Search, Depth-first Search |      |
-| 144  | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/)                 | [Java](./Java/binary-tree-preorder-traversal.java)                                                               | _O(n)_      | _O(logn)_   | Medium     | Binary Tree, Stack                             |      |
+| 144  | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/)                 | [Java](./Java/binary-tree-preorder-traversal.java) <br> [C++](./C++/Binary-Tree-Preorder-Traversal.cpp)         | _O(n)_      | _O(logn)_   | Medium     | Binary Tree, Stack                             |      |
 | 145  | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/)               | [Java](./Java/binary-tree-postorder-traversal.java)                                                              | _O(n)_      | _O(logn)_   | Hard       | Binary Tree, Stack                             |      |
 | 103  | [ZigZag Level Order](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/)                   | [JavaScript](./JavaScript/Binary-Tree-ZigZag-Traversal.js) <br> [C++](./C++/binary-tree-preorder-traversal.java) | _O(n)_      | _O(n)_      | Medium     | Binary Tree                                    |      |
 | 129  | [Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers/)                             | [Java](./Java/sum-root-to-leaf-numbers.java)                                                                     | _O(n)_      | _O(logn)_   | Medium     | Binary Tree, Depth First Search                |      |