109 lines
4.8 KiB
C#
109 lines
4.8 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using static System.Console;
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namespace ZebraPuzzleSolver
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{
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public enum Colour { Red, Green, White, Yellow, Blue }
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public enum Nationality { Englishman, Swede, Dane, Norwegian, German }
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public enum Pet { Dog, Birds, Cats, Horse, Zebra }
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public enum Drink { Coffee, Tea, Milk, Beer, Water }
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public enum Smoke { PallMall, Dunhill, Blend, BlueMaster, Prince }
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public struct House
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{
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public Drink D { get; }
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public Colour C { get; }
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public Pet P { get; }
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public Nationality N { get; }
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public Smoke S { get; }
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House(Drink d, Colour c, Pet p, Nationality n, Smoke s) => (D, C, P, N, S) = (d, c, p, n, s);
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public static House Create(Drink d, Colour c, Pet p, Nationality n, Smoke s) => new House(d, c, p, n, s);
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public bool AllUnequal(House other) => D != other.D && C != other.C && P != other.P && N != other.N && S != other.S;
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public override string ToString() =>$"{C,-6} {D,-8} {N,-11} {S,-10} {P,-10}";
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}
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public static class LinqNoPerm
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{
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public static IEnumerable<T> ToEnumerable<T>() => Enum.GetValues(typeof(T)).Cast<T>();
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public static IEnumerable<House> FreeCandidates(this IEnumerable<House> houses, IEnumerable<House> picked) =>
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houses.Where(house => picked.All(house.AllUnequal));
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static Dictionary<Type, Func<House, dynamic, bool>> _eFn = new Dictionary<Type, Func<House, dynamic, bool>>
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{ {typeof(Drink),(h,e)=>h.D==e},
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{typeof(Nationality),(h,e)=>h.N==e},
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{typeof(Colour),(h,e)=>h.C==e},
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{typeof(Pet),(h,e)=>h.P==e},
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{typeof(Smoke),(h, e)=>h.S==e}
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};
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public static bool IsNextTo<T, U>(this IEnumerable<House> hs,T t, U u) => hs.IsLeftOf(t,u) || hs.IsLeftOf(u, t);
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public static bool IsLeftOf<T, U>(this IEnumerable<House> hs, T left, U right) =>
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hs.Zip(hs.Skip(1), (l, r) => (_eFn[left.GetType()](l, left) && _eFn[right.GetType()](r, right))).Any(l => l);
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static House[] _solved;
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static LinqNoPerm()
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{
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var candidates =
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from colours in ToEnumerable<Colour>()
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from nations in ToEnumerable<Nationality>()
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from drinks in ToEnumerable<Drink>()
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from pets in ToEnumerable<Pet>()
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from smokes in ToEnumerable<Smoke>()
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where (colours == Colour.Red) == (nations == Nationality.Englishman) //r2
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where (nations == Nationality.Swede) == (pets == Pet.Dog) //r3
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where (nations == Nationality.Dane) == (drinks == Drink.Tea) //r4
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where (colours == Colour.Green) == (drinks == Drink.Coffee) //r6
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where (smokes == Smoke.PallMall) == (pets == Pet.Birds) //r7
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where (smokes == Smoke.Dunhill) == (colours == Colour.Yellow) // r8
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where (smokes == Smoke.BlueMaster) == (drinks == Drink.Beer) //r13
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where (smokes == Smoke.Prince) == (nations == Nationality.German) // r14
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select House.Create(drinks,colours,pets,nations, smokes);
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var members =
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from h1 in candidates
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where h1.N == Nationality.Norwegian //r10
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from h3 in candidates.FreeCandidates(new[] { h1 })
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where h3.D == Drink.Milk //r9
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from h2 in candidates.FreeCandidates(new[] { h1, h3 })
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let h123 = new[] { h1, h2, h3 }
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where h123.IsNextTo(Nationality.Norwegian, Colour.Blue) //r15
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where h123.IsNextTo(Smoke.Blend, Pet.Cats)//r11
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where h123.IsNextTo(Smoke.Dunhill, Pet.Horse) //r12
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from h4 in candidates.FreeCandidates(h123)
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from h5 in candidates.FreeCandidates(new[] { h1, h3, h2, h4 })
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let houses = new[] { h1, h2, h3, h4, h5 }
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where houses.IsLeftOf(Colour.Green, Colour.White) //r5
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select houses;
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_solved = members.First();
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}
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public static new String ToString()
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{
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var sb = new StringBuilder();
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sb.AppendLine("House Colour Drink Nationality Smokes Pet");
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sb.AppendLine("───── ────── ──────── ─────────── ────────── ─────");
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for (var i = 0; i < 5; i++)
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sb.AppendLine($"{i + 1,5} {_solved[i].ToString()}");
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return sb.ToString();
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}
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public static void Main(string[] arguments)
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{
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var owner = _solved.Where(h=>h.P==Pet.Zebra).Single().N;
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WriteLine($"The zebra owner is {owner}");
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Write(ToString());
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Read();
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}
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}
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}
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