namespace IStation
|
{
|
// 算法:排列组合类
|
//
|
// 版权所有(C) Snowdust
|
// 个人博客 http://blog.csdn.net/snowdust & http://snowdust.cnblogs.com
|
// MSN & Email snowdust77@sina.com
|
//
|
// 此源代码可免费用于各类软件（含商业软件）
|
// 允许对此代码的进一步修改与开发
|
// 但必须完整保留此版权信息
|
//
|
// 调用方法如下:
|
//
|
// 1.GetPermutation(T[], startIndex, endIndex)
|
// 对startIndex到endIndex进行排列，其余元素不变
|
//
|
// 2.GetPermutation(T[])
|
// 返回数组所有元素的全排列
|
//
|
// 3.GetPermutation(T[], n)
|
// 返回数组中n个元素的排列
|
//
|
// 4.GetCombination(T[], n)
|
// 返回数组中n个元素的组合
|
|
//使用实例
|
//int[] arr = new int[6];
|
//for (int i = 0; i < arr.Length; i++)
|
//{
|
// arr[i] = i + 1;
|
//}
|
////求排列
|
//List<int[]> lst_Permutation = Eventech.Model.PermutationAndCombination<int>.GetPermutation(arr, 3);
|
////求组合
|
//List<int[]> lst_Combination = Eventech.Model.PermutationAndCombination<int>.GetCombination(arr, 3);
|
|
|
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;
|
}
|
}
|
}
|
