How Can We Efficiently Shuffle an Integer List in C#?

Efficient random sorting algorithm for C# integer list

This article explores a more efficient way to randomly sort or shuffle a list of integers.

Fisher-Yates Shuffling Algorithm

The Fisher-Yates shuffling algorithm is a linear-time algorithm that efficiently randomizes lists. Here’s how it works:

For each index i in the list from 0 to n-1, do the following:

<code>int j = random.Next(i + 1);
交换索引i和j处的数值;</code>

Improve existing problems in the algorithm

The proposed algorithm has some shortcomings:

• Inefficiency at the end: As the algorithm progresses, it becomes increasingly difficult to find unswapped elements, leading to inefficiency.
• Infinite loop: When the number of elements is an odd number, the algorithm will not terminate because it cannot find a suitable exchange candidate.

Code implementation

The following code snippet implements the Fisher-Yates shuffling algorithm in C#:

using System;
using System.Collections.Generic;

class Program
{
    static void Shuffle<T>(IList<T> list)
    {
        Random random = new Random();

        for (int i = 0; i < list.Count; i++)
        {
            int j = random.Next(i + 1);
            T temp = list[i];
            list[i] = list[j];
            list[j] = temp;
        }
    }

    static void Main(string[] args)
    {
        List<int> values = new List<int>();
        for (int i = 0; i < 10; i++)
        {
            values.Add(i);
        }

        Shuffle(values);

        Console.WriteLine(string.Join(", ", values));
    }
}

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