Add Josephus Problem in C# (#3979)

archive/c/c-sharp/JosephusProblem.cs

@@ -0,0 +1,40 @@
+using System;
+
+namespace JosephusProblem
+{
+    class Program
+    {
+        const string Usage = "Usage: please input the total number of people and number of people to skip.";
+
+        static void Main(string[] args)
+        {
+            if (args.Length < 2)
+            {
+                Console.WriteLine(Usage);
+                return;
+            }
+
+            if (!int.TryParse(args[0], out int n) || !int.TryParse(args[1], out int k) || n <= 0 || k <= 0)
+            {
+                Console.WriteLine(Usage);
+                return;
+            }
+
+            int survivor = FindJosephusPosition(n, k);
+
+            Console.WriteLine(survivor);
+        }
+
+        static int FindJosephusPosition(int n, int k)
+        {
+            int result = 0;
+
+            for (int m = 2; m <= n; m++)
+            {
+                result = (result + k) % m;
+            }
+
+            return result + 1;
+        }
+    }
+}