Day10

144. Binary Tree Preorder Traversal/144. Binary Tree Preorder Traversal.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_144._Binary_Tree_Preorder_Traversal</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

144. Binary Tree Preorder Traversal/Program.cs

@@ -0,0 +1,9 @@
+namespace _144._Binary_Tree_Preorder_Traversal;
+
+internal class Program
+{
+    static void Main(string[] args)
+    {
+        Console.WriteLine("Hello, World!");
+    }
+}

144. Binary Tree Preorder Traversal/Solution.cs

@@ -0,0 +1,22 @@
+namespace _144._Binary_Tree_Preorder_Traversal;
+
+public class Solution
+{
+    public IList<int> PreorderTraversal(TreeNode root)
+    {
+        List<int> res = new List<int>();
+        Stack<TreeNode> stack = new Stack<TreeNode>();
+        if (root != null)
+            stack.Push(root);
+        while (stack.Count > 0)
+        {
+            TreeNode cur = stack.Pop();
+            if (cur.right != null)
+                stack.Push(cur.right);
+            if (cur.left != null)
+                stack.Push(cur.left);
+            res.Add(cur.val);
+        }
+        return res;
+    }
+}

144. Binary Tree Preorder Traversal/TreeNode.cs

@@ -0,0 +1,16 @@
+namespace _144._Binary_Tree_Preorder_Traversal;
+
+
+//Definition for a binary tree node.
+public class TreeNode
+{
+    public int val;
+    public TreeNode? left;
+    public TreeNode? right;
+    public TreeNode(int val = 0, TreeNode? left = null, TreeNode? right = null)
+    {
+        this.val = val;
+        this.left = left;
+        this.right = right;
+    }
+}