Data commit

Task/Recamans-sequence/C-sharp/recamans-sequence.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+
+namespace RecamanSequence {
+    class Program {
+        static void Main(string[] args) {
+            List<int> a = new List<int>() { 0 };
+            HashSet<int> used = new HashSet<int>() { 0 };
+            HashSet<int> used1000 = new HashSet<int>() { 0 };
+            bool foundDup = false;
+            int n = 1;
+            while (n <= 15 || !foundDup || used1000.Count < 1001) {
+                int next = a[n - 1] - n;
+                if (next < 1 || used.Contains(next)) {
+                    next += 2 * n;
+                }
+                bool alreadyUsed = used.Contains(next);
+                a.Add(next);
+                if (!alreadyUsed) {
+                    used.Add(next);
+                    if (0 <= next && next <= 1000) {
+                        used1000.Add(next);
+                    }
+                }
+                if (n == 14) {
+                    Console.WriteLine("The first 15 terms of the Recaman sequence are: [{0}]", string.Join(", ", a));
+                }
+                if (!foundDup && alreadyUsed) {
+                    Console.WriteLine("The first duplicated term is a[{0}] = {1}", n, next);
+                    foundDup = true;
+                }
+                if (used1000.Count == 1001) {
+                    Console.WriteLine("Terms up to a[{0}] are needed to generate 0 to 1000", n);
+                }
+                n++;
+            }
+        }
+    }
+}