Day10

145. Binary Tree Postorder Traversal/145. Binary Tree Postorder Traversal.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_145._Binary_Tree_Postorder_Traversal</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

145. Binary Tree Postorder Traversal/Program.cs

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+namespace _145._Binary_Tree_Postorder_Traversal;
+
+internal class Program
+{
+    static void Main(string[] args)
+    {
+        Console.WriteLine("Hello, World!");
+    }
+}

145. Binary Tree Postorder Traversal/Solution.cs

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+namespace _145._Binary_Tree_Postorder_Traversal;
+
+public class Solution
+{
+    public IList<int> PostorderTraversal(TreeNode root)
+    {
+        var result = new List<int>();
+        if (root == null) return result;
+        var stack = new Stack<TreeNode>();
+        stack.Push(root);
+        while (stack.Any())
+        {
+            var cur = stack.Pop();
+            result.Add(cur.val);
+            if (cur.left != null)
+                stack.Push(cur.left);
+            if (cur.right != null)
+                stack.Push(cur.right);
+        }
+        result.Reverse();
+
+        return result;
+    }
+}

145. Binary Tree Postorder Traversal/TreeNode.cs

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+namespace _145._Binary_Tree_Postorder_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;
+    }
+}