added new exercices

Algorithms/IdCard/TelephonNumber.cs

@@ -0,0 +1,21 @@
+using System.Text.RegularExpressions;
+
+namespace Algorithms.IdCard;
+
+public class TelephonNumber
+{
+    private string telephonNumber;
+
+    public TelephonNumber(string telephonNumber)
+    {
+        this.telephonNumber = telephonNumber;
+    }
+
+
+
+    public bool IsValid(){
+        Regex rx = new Regex(@"^(\+?1 )?\d{3} \d{3}-\d{4}$");
+        return rx.Match(this.telephonNumber).Success;
+    }
+
+}