Question

How to shuffle (random) a list in C#

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication_C_Sharp
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

            var rnd = new Random();
            var r = list.OrderBy(item => rnd.Next());

            Console.WriteLine(String.Join(" ", r));
        }
    }
}


/*
run:

2 4 1 6 8 7 9 3 5

*/

 

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Answer 2

using System;
using System.Collections.Generic;

namespace ConsoleApplication_C_Sharp
{
    public static class SF
    {
        public static void Shuffle<T>(this IList<T> list)
        {
            int count = list.Count;
            Random rnd = new Random();
            while (count > 1) {
                int k = (rnd.Next(0, count) % count);
                count--;
                T value = list[k];
                list[k] = list[count];
                list[count] = value;
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

            SF.Shuffle(list);

            Console.WriteLine(String.Join(" ", list));
        }
       
    }
    
}


/*
run:

8 7 3 1 4 6 5 2 9

*/

 

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Answer 3

using System;
using System.Collections.Generic;

namespace ConsoleApplication_C_Sharp
{
    public static class SFL
    {
        public static void Shuffle<T>(this IList<T> list)
        {
            int count = list.Count;
            Random rnd = new Random();
            while (count > 1) {
                count--;
                int n = rnd.Next(count + 1);
                T value = list[n];
                list[n] = list[count];
                list[count] = value;
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

            SFL.Shuffle(list);

            Console.WriteLine(String.Join(" ", list));
        }
    }
}


/*
run:

9 1 6 5 7 2 8 4 3

*/

 

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