public static T[,] Random <T>(this T[,] array)
{
if (array == null)
{
throw CommonExceptions.ArgumentNull("array");
}
Contract.Ensures(Contract.Result <T[, ]>() != null);
int w = array.GetLength(1);
int idx = array.Length;
for (int i = array.GetLength(0) - 1; i >= 0; i--)
{
for (int j = w - 1; j >= 0; j--)
{
int r = RandomExt.Next(idx--);
int x = r % w;
int y = r / w;
if (y != i || x != j)
{
T temp = array[i, j];
array[i, j] = array[y, x];
array[y, x] = temp;
}
}
}
return(array);
}
/// <summary>
/// 将数组进行随机排序。
/// </summary>
/// <typeparam name="T">数组中元素的类型。</typeparam>
/// <param name="array">要进行随机排序的数组。</param>
/// <returns>已完成随机排序的数组。</returns>
/// <remarks>应保证每个元素出现在每个位置的概率基本相同。
/// 采用下面的代码进行测试：
/// <code>int size = 10;
/// int[] arr = new int[size];
/// int[,] cnt = new int[size, size];
/// for (int i = 0; i { 200; i++)
/// {
/// arr.Fill(n => n).Random();
/// for (int j = 0; j { size; j++) cnt[j, arr[j]]++;
/// }
/// for (int i = 0; i { size; i++)
/// {
/// for (int j = 0; j { size; j++)
/// Console.Write("{0} ", cnt[i, j]);
/// Console.WriteLine();
/// }</code>
/// </remarks>
/// <overloads>
/// <summary>
/// 将数组进行随机排序。
/// </summary>
/// </overloads>
public static T[] Random <T>(this T[] array)
{
if (array == null)
{
throw CommonExceptions.ArgumentNull("array");
}
Contract.Ensures(Contract.Result <T[]>() != null);
for (int i = array.Length - 1; i > 0; i--)
{
int j = RandomExt.Next(i + 1);
if (j != i)
{
T temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}
return(array);
}
