Data commit

Task/Kolakoski-sequence/C-sharp/kolakoski-sequence.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace KolakoskiSequence {
+    class Crutch {
+        public readonly int len;
+        public int[] s;
+        public int i;
+
+        public Crutch(int len) {
+            this.len = len;
+            s = new int[len];
+            i = 0;
+        }
+
+        public void Repeat(int count) {
+            for (int j = 0; j < count; j++) {
+                if (++i == len) return;
+                s[i] = s[i - 1];
+            }
+        }
+    }
+
+    static class Extension {
+        public static int NextInCycle(this int[] self, int index) {
+            return self[index % self.Length];
+        }
+
+        public static int[] Kolakoski(this int[] self, int len) {
+            Crutch c = new Crutch(len);
+
+            int k = 0;
+            while (c.i < len) {
+                c.s[c.i] = self.NextInCycle(k);
+                if (c.s[k] > 1) {
+                    c.Repeat(c.s[k] - 1);
+                }
+                if (++c.i == len) return c.s;
+                k++;
+            }
+            return c.s;
+        }
+
+        public static bool PossibleKolakoski(this int[] self) {
+            int[] rle = new int[self.Length];
+            int prev = self[0];
+            int count = 1;
+            int pos = 0;
+            for (int i = 1; i < self.Length; i++) {
+                if (self[i] == prev) {
+                    count++;
+                }
+                else {
+                    rle[pos++] = count;
+                    count = 1;
+                    prev = self[i];
+                }
+            }
+            // no point adding final 'count' to rle as we're not going to compare it anyway
+            for (int i = 0; i < pos; i++) {
+                if (rle[i] != self[i]) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        public static string AsString(this int[] self) {
+            StringBuilder sb = new StringBuilder("[");
+            int count = 0;
+            foreach (var item in self) {
+                if (count > 0) {
+                    sb.Append(", ");
+                }
+                sb.Append(item);
+                count++;
+            }
+            return sb.Append("]").ToString();
+        }
+    }
+
+    class Program {
+        static void Main(string[] args) {
+            int[][] ias = {
+                new int[]{1, 2},
+                new int[]{2, 1},
+                new int[]{1, 3, 1, 2},
+                new int[]{1, 3, 2, 1}
+            };
+            int[] lens = { 20, 20, 30, 30 };
+
+            for (int i = 0; i < ias.Length; i++) {
+                int len = lens[i];
+                int[] kol = ias[i].Kolakoski(len);
+
+                Console.WriteLine("First {0} members of the sequence by {1}: ", len, ias[i].AsString());
+                Console.WriteLine(kol.AsString());
+                Console.WriteLine("Possible Kolakoski sequence? {0}", kol.PossibleKolakoski());
+                Console.WriteLine();
+            }
+        }
+    }
+}