add Programmyday form github

DoppelteBuchstaben/DoppelteBuchstaben.csproj

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

DoppelteBuchstaben/DuplicateChars.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace DoppelteBuchstaben
+{
+    internal class DuplicateChars
+    {
+        private string _text;
+        public bool ContainsDuplicateChars(string text)
+        {
+            for (int i = 0; i < text.Length; i++)
+            {
+                for (int j = i + 1; j < text.Length; j++)
+                {
+                    if (text[i] == text[j])
+                    {
+                        return true;
+                    }
+                }
+            }
+            return false;
+        }
+        public string RemoveDuplicateChars(string text)
+        {
+            for (int i = 0; i < text.Length; i++)
+            {
+                for (int j = i + 1; j < text.Length; j++)
+                {
+                    if (text[i] == text[j])
+                    {
+                        this._text = text.Remove(j);
+                        return this._text;
+                    }
+                }
+            }
+            return text; 
+        }
+    }
+}

DoppelteBuchstaben/Program.cs

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+namespace DoppelteBuchstaben
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            DuplicateChars duplicate = new DuplicateChars();
+            string text = Console.ReadLine();
+            Console.WriteLine(duplicate.ContainsDuplicateChars(text));
+            Console.WriteLine(duplicate.RemoveDuplicateChars(text));
+        }
+    }
+}