给定一个正整数n，需要输出一个长度为n的数组，数组元素是随机数，范围为0 – n-1，且元素不能重复。比如 n = 3 时，需要获取一个长度为3的数组，元素范围为0-2；简单的理解就是生成一个无序的随机数组。

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace RandomNumber

{

class Program

{

static void Main(string[] args)

{

//初始化一个数组，如果数组没有赋值，默认是0

//int[] arr = SolveProblemWayOne(5);

//int[] arr = SolveProblemWaySecond(5);

//int[] arr = SolveProblemWayThird(10);

int[] arr = SolveProblemWayFour(5);

for (int i = 0; i < arr.Length; i++)

{

Console.Write("{0,5}", arr[i].ToString());

}

Console.ReadKey();

}

/// <summary>

/// 循环判断随机出来的数字是否在数组中

/// </summary>

/// <param name="total"></param>

/// <returns></returns>

public static int[] SolveProblemWayOne(int count)

{

List<int> resultList = new List<int>();

Random random = new Random();

for (int i = 0; i < count; i++)

{

int number = random.Next(1, count + 1);

while (resultList.Contains(number))

{

number = random.Next(1, count + 1);

}

resultList.Add(number);

}

return resultList.ToArray();

}

/// <summary>

/// 按照顺序生成一个数组

/// </summary>

/// <param name="total"></param>

/// <returns></returns>

public static int[] SolveProblemWaySecond(int count)

{

List<int> orignalList = new List<int>();

List<int> resultList = new List<int>();

for (int i = 0; i < count; i++)

{

orignalList.Add(i);

}

int maxIndex = count;

Random random = new Random();

for (int i = 0; i < count; i++)

{

//随机索引

int index = random.Next(0, maxIndex);

resultList.Add(orignalList[index]);

orignalList.RemoveAt(index);

maxIndex--;

}

return resultList.ToArray();

}

/// <summary>

/// 不删除数据，然后的问题就是给最后的东西赋值

/// </summary>

/// <param name="count"></param>

/// <returns></returns>

public static int[] SolveProblemWayThird(int count)

{

List<int> orignalList = new List<int>();

List<int> resultList = new List<int>();

for (int i = 0; i < count; i++)

{

orignalList.Add(i);

}

int minIndex = 0;

Random random = new Random();

for (int i = 0; i < count; i++)

{

//随机索引

int index = random.Next(minIndex, count);

resultList.Add(orignalList[index]);

//交换，由于索引自减，不需要将随机的值赋值到最后

//int temp = orignalList[index];

orignalList[index] = orignalList[minIndex];

//orignalList[minIndex] = temp;

minIndex++;

}

return resultList.ToArray();

}

/// <summary>

/// 简洁方式

/// </summary>

/// <param name="count"></param>

/// <returns></returns>

public static int[] SolveProblemWayFour(int count)

{

List<int> resultList = new List<int>();

for (int i = 0; i < count; i++)

{

resultList.Add(i);

}

int minIndex = 0;

Random random = new Random();

for (int i = 0; i < count; i++)

{

//随机索引

int index = random.Next(minIndex, count);

//头部交换

int temp = resultList[index];

resultList[index] = resultList[minIndex];

resultList[minIndex] = temp;

minIndex++;

}

return resultList.ToArray();

}

}

}