烙饼排序问题最优次数求解 暑期学习笔记（九）

将直径不同的烙饼有序排列的问题，求取最优解需要的反转次数。

代码：

Code

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace CakeSorting

{

class Program

{

private int[] cakeSizeArray;//大饼直径队列

private int[] cakeArray;//大饼队列

const int cakeNum = 5;

private int maxTime = 0;

static void Main(string[] args)

{

Program p = new Program();

p.run();

}

void run()

{

init();

search(0);

Console.WriteLine("maxtime is :{0}", maxTime);

Console.ReadLine();

}

void init()

{

//初始化赋值

maxTime = 2 * (cakeNum - 1);

cakeArray = new int[cakeNum];

cakeSizeArray = new int[cakeNum];

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

{

cakeSizeArray[i] = i;

}//大饼直径初始化

randomCollection();

//队列初始化完毕

}

void randomCollection()

{

if (cakeSizeArray.Length != cakeArray.Length)

return;

Random r = new Random();

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

{

cakeArray[i] = cakeSizeArray[0];

}

for (int i = 1; i < cakeSizeArray.Length; i++)

{

int address = r.Next(10);

for(;;)

{

if (address >= cakeSizeArray.Length)

address = 0;

if (cakeArray[address] != cakeSizeArray[0])

address++;

else

break;

}

cakeArray[address] = cakeSizeArray[i];

}

//打印结果

Console.WriteLine("Cake Array:");

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

{

Console.Write("{0}\t", cakeArray[i]);

}

}

void search(int step)

{

if (step > maxTime)

return;//大于2（n-1）时退出

for (int i = 1; cakeArray [i-1]<cakeArray [i]; i++)

{

if (i == cakeArray.Length - 1)

{

maxTime = step;

return;

}

}//排序成功退出

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

{

revert(0, i);

search(step+1);

revert(0, i);

}//递归穷举所有方案

}

void revert(int begin, int end)

{

int t = cakeArray[begin];

for (int i = begin, j = end; i < j; i++, j--)

{

t = cakeArray[i];

cakeArray[i] = cakeArray[j];

cakeArray[j] = t;

}

}

}

}