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Initial data commit

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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 72d218235f
commit f23f22d71c
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43
Task/N-queens-problem/C-sharp/n-queens-problem-1.cs Normal file
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using System.Collections.Generic;
using static System.Linq.Enumerable;
using static System.Console;
using static System.Math;
namespace N_Queens
{
static class Program
{
static void Main(string[] args)
{
var n = 8;
var cols = Range(0, n);
var combs = cols.Combinations(2).Select(pairs=> pairs.ToArray());
var solved = from v in cols.Permutations().Select(p => p.ToArray())
where combs.All(c => Abs(v[c[0]] - v[c[1]]) != Abs(c[0] - c[1]))
select v;
WriteLine($"{n}-queens has {solved.Count()} solutions");
WriteLine("Position is row, value is column:-");
var first = string.Join(" ", solved.First());
WriteLine($"First Solution: {first}");
Read();
}
//Helpers
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<IEnumerable<T>> Combinations<T>(this IEnumerable<T> seq) =>
seq.Aggregate(Empty<T>().ToSingleton(), (a, b) => a.Concat(a.Select(x => x.Append(b))));
public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> seq, int numItems) =>
seq.Combinations().Where(s => s.Count() == numItems);
public static IEnumerable<T> ToSingleton<T>(this T item) { yield return item; }
}
}

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Task/N-queens-problem/C-sharp/n-queens-problem-2.cs Normal file
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using System.Collections.Generic;
using static System.Linq.Enumerable;
using static System.Console;
using static System.Math;
namespace N_Queens
{
static class Program
{
static void Main(string[] args)
{
var n = 8;
var cols = Range(0, n);
var solved = from v in cols.Permutations().Select(p => p.ToArray())
where n == (from i in cols select v[i]+i).Distinct().Count()
where n == (from i in cols select v[i]-i).Distinct().Count()
select v;
WriteLine($"{n}-queens has {solved.Count()} solutions");
WriteLine("Position is row, value is column:-");
var first = string.Join(" ", solved.First());
WriteLine($"First Solution: {first}");
Read();
}
//Helpers from https://gist.github.com/martinfreedman/139dd0ec7df4737651482241e48b062f
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; }
}
}

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Task/N-queens-problem/C-sharp/n-queens-problem-3.cs Normal file
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using static System.Linq.Enumerable;
using static System.Console;
namespace N_Queens
{
static class Program
{
static void Main(string[] args)
{
var n = 8;
var domain = Range(0, n).ToArray();
var amb = new Amb.Amb();
var queens = domain.Select(_ => amb.Choose(domain)).ToArray();
amb.Require(() => n == queens.Select(q=> q.Value).Distinct().Count());
amb.Require(() => n == domain.Select(i=> i + queens[i].Value).Distinct().Count());
amb.Require(() => n == domain.Select(i=> i - queens[i].Value).Distinct().Count());
if (amb.Disambiguate())
{
WriteLine("Position is row, value is column:-");
WriteLine(string.Join(" ", queens.AsEnumerable()));
}
else
WriteLine("amb is angry");
Read();
}
}
}