.net C# 实现任意List的笛卡尔乘积算法代码
本文导语: 可以扩展到多个集合的情况。类似的例子有,如果A表示某学校学生的集合,B表示该学校所有课程的集合,则A与B的笛卡尔积表示所有可能的选课情况 代码如下:using System;using System.Collections.Generic;using System.Diagnostics;using System.Li...
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace 算法
{
public static class 算法
{
///
/// 笛卡尔乘积
///
public static List CartesianProduct(this List lstSplit)
{
int count = 1;
lstSplit.ForEach(item => count *= item.Count);
//count = lstSplit.Aggregate(1, (result, next) => result * next.Count);
var lstResult = new List();
for (int i = 0; i < count; ++i)
{
var lstTemp = new List();
int j = 1;
lstSplit.ForEach(item =>
{
j *= item.Count;
lstTemp.Add(item[(i / (count / j)) % item.Count]);
});
lstResult.Add(lstTemp);
}
return lstResult;
}
}
class Program
{
public static void Main()
{
StringDemo();
根据Sector生成Routing的Demo();
根据Sector生成Routing的Demo2();
}
///
/// 简单字符串 笛卡尔乘积
///
private static void StringDemo()
{
var lstSource = new List
{
new List() { "A","B","C"},
new List() { "D","E","F"},
new List() { "G","H","I"},
};
var sw = new Stopwatch();
sw.Start();
var lstResult = lstSource.CartesianProduct();
Console.WriteLine(sw.Elapsed);
}
private static void 根据Sector生成Routing的Demo()
{
//默认允许输入多个BookingClass,表示使用任意一个都可以。
var lstSectorDef = new List
{
new Sector{ SeqNO=1, BookingClass="A/A1/A2"},
new Sector{ SeqNO=2, BookingClass="B/B1/B2"},
new Sector{ SeqNO=3, BookingClass="C/C1/C2"},
//.....数量不定
};
var sw = new Stopwatch();
sw.Start();
var lstSectorGroup = new List();
lstSectorDef.ForEach(item =>
{
var lstSector = new List();
foreach (var bookingClass in item.BookingClass.Split('/'))
{
var sector = item.Clone();
sector.BookingClass = bookingClass;
lstSector.Add(sector);
}
lstSectorGroup.Add(lstSector);
});
var lstRouting = lstSectorGroup.CartesianProduct();
Console.WriteLine(sw.Elapsed);
}
private static void 根据Sector生成Routing的Demo2()
{
//默认允许输入多个BookingClass,表示使用任意一个都可以。
var lstSectorDef = new List
{
new Sector{ SeqNO=1, BookingClass="A1/A2/A3"},
new Sector{ SeqNO=2, BookingClass="B1/B2/B3"},
new Sector{ SeqNO=3, BookingClass="C1/C2/C3"},
//.....数量不定
};
var sw = new Stopwatch();
sw.Start();
var lstTemp = new List();
lstSectorDef.ForEach(item =>
{
lstTemp.Add(item.BookingClass.Split('/').ToList());
});
var lstBookingClassGroup = lstTemp.CartesianProduct();
var lstRouting = new List();
for (int i = 0; i < lstBookingClassGroup.Count; i++)
{
var lstSector = new List();
for (int j = 0; j < lstSectorDef.Count; j++)
{
var sector = lstSectorDef[j].Clone();
sector.BookingClass = lstBookingClassGroup[i][j];
lstSector.Add(sector);
}
lstRouting.Add(lstSector);
}
Console.WriteLine(sw.Elapsed);
}
}
[DebuggerDisplay("Sector:SeqNO={SeqNO},BookingClass={BookingClass}")]
public class Sector
{
public int SeqNO { get; set; }
public string BookingClass { get; set; }
public Sector Clone()
{
return this.MemberwiseClone() as Sector;
}
}
}