June 2018 Update

Task/Dinesmans-multiple-dwelling-problem/C-sharp/dinesmans-multiple-dwelling-problem-2.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using static System.Linq.Enumerable;
+
+static class Program
+{
+    enum Tenants { Baker = 0, Cooper = 1, Fletcher = 2, Miller = 3, Smith = 4 };
+
+    static void Main()
+    {
+        var count = Enum.GetNames(typeof(Tenants)).Length;
+        var top = count - 1;
+
+        var solve =
+            from f in Range(0, count).Permutations()
+            let floors = f.ToArray()
+            where floors[(int)Tenants.Baker] != top //r1
+            where floors[(int)Tenants.Cooper] != 0 //r2
+            where floors[(int)Tenants.Fletcher] != top && floors[(int)Tenants.Fletcher] != 0 //r3
+            where floors[(int)Tenants.Miller] > floors[(int)Tenants.Cooper] //r4
+            where Math.Abs(floors[(int)Tenants.Smith] - floors[(int)Tenants.Fletcher]) !=1 //r5
+            where Math.Abs(floors[(int)Tenants.Fletcher] - floors[(int)Tenants.Cooper]) !=1 //r6
+            select floors;
+        var solved = solve.First();
+        var output = Range(0,count).OrderBy(i=>solved[i]).Select(f => ((Tenants)f).ToString());
+        Console.WriteLine(String.Join(" ", output));
+        Console.Read();
+    }
+
+    public static IEnumerable<IEnumerable<T>> Permutations<T>(this IEnumerable<T> values)
+    {
+        if (values.Count() == 1)
+            return values.ToSingleton();
+
+        return values.SelectMany(v => Permutations(values.Except(v.ToSingleton())), (v, p) => p.Prepend(v));
+    }
+
+    public static IEnumerable<T> ToSingleton<T>(this T item) { yield return item; }
+}