C#排列组合类，写彩票算法的朋友们可以来看一看

public class PermutationAndCombination<T>

{

/// <summary>

/// 交换两个变量

/// </summary>

/// <param name="a">变量1</param>

/// <param name="b">变量2</param>

public static void Swap(ref T a, ref T b)

{

T temp = a;

a = b;

b = temp;

}

/// <summary>

/// 递归算法求数组的组合(私有成员)

/// </summary>

/// <param name="list">返回的范型</param>

/// <param name="t">所求数组</param>

/// <param name="n">辅助变量</param>

/// <param name="m">辅助变量</param>

/// <param name="b">辅助数组</param>

/// <param name="M">辅助变量M</param>

private static void GetCombination(ref List<T[]> list, T[] t, int n, int m, int[] b, int M)

{

for (int i = n; i >= m; i--)

{

b[m - 1] = i - 1;

if (m > 1)

{

GetCombination(ref list, t, i - 1, m - 1, b, M);

}

else

{

if (list == null)

{

list = new List<T[]>();

}

T[] temp = new T[M];

for (int j = 0; j < b.Length; j++)

{

temp[j] = t[b[j]];

}

list.Add(temp);

}

}

}

/// <summary>

/// 递归算法求排列(私有成员)

/// </summary>

/// <param name="list">返回的列表</param>

/// <param name="t">所求数组</param>

/// <param name="startIndex">起始标号</param>

/// <param name="endIndex">结束标号</param>

private static void GetPermutation(ref List<T[]> list, T[] t, int startIndex, int endIndex)

{

if (startIndex == endIndex)

{

if (list == null)

{

list = new List<T[]>();

}

T[] temp = new T[t.Length];

t.CopyTo(temp, 0);

list.Add(temp);

}

else

{

for (int i = startIndex; i <= endIndex; i++)

{

Swap(ref t[startIndex], ref t[i]);

GetPermutation(ref list, t, startIndex + 1, endIndex);

Swap(ref t[startIndex], ref t[i]);

}

}

}

/// <summary>

/// 求从起始标号到结束标号的排列，其余元素不变

/// </summary>

/// <param name="t">所求数组</param>

/// <param name="startIndex">起始标号</param>

/// <param name="endIndex">结束标号</param>

/// <returns>从起始标号到结束标号排列的范型</returns>

public static List<T[]> GetPermutation(T[] t, int startIndex, int endIndex)

{

if (startIndex < 0 || endIndex > t.Length - 1)

{

return null;

}

List<T[]> list = new List<T[]>();

GetPermutation(ref list, t, startIndex, endIndex);

return list;

}

/// <summary>

/// 返回数组所有元素的全排列

/// </summary>

/// <param name="t">所求数组</param>

/// <returns>全排列的范型</returns>

public static List<T[]> GetPermutation(T[] t)

{

return GetPermutation(t, 0, t.Length - 1);

}

/// <summary>

/// 求数组中n个元素的排列

/// </summary>

/// <param name="t">所求数组</param>

/// <param name="n">元素个数</param>

/// <returns>数组中n个元素的排列</returns>

public static List<T[]> GetPermutation(T[] t, int n)

{

if (n > t.Length)

{

return null;

}

List<T[]> list = new List<T[]>();

List<T[]> c = GetCombination(t, n);

for (int i = 0; i < c.Count; i++)

{

List<T[]> l = new List<T[]>();

GetPermutation(ref l, c[i], 0, n - 1);

list.AddRange(l);

}

return list;

}

/// <summary>

/// 求数组中n个元素的组合

/// </summary>

/// <param name="t">所求数组</param>

/// <param name="n">元素个数</param>

/// <returns>数组中n个元素的组合的范型</returns>

public static List<T[]> GetCombination(T[] t, int n)

{

if (t.Length < n)

{

return null;

}

int[] temp = new int[n];

List<T[]> list = new List<T[]>();

GetCombination(ref list, t, t.Length, n, temp, n);

return list;

}

}

调用：

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

{

arr[i] = i + 1;

}

//求排列

List<int[]> lst_Permutation = Algorithms.PermutationAndCombination<int>.GetPermutation(arr, 3);//包含重复的

//求组合

List<int[]> lst_Combination = Algorithms.PermutationAndCombination<int>.GetCombination(arr, 3);//不包含重复的