#include <iostream>
#include <cstdlib>
#include <time.h>
#include <math.h>
#define MAXN 10000
#define LIMIT 500
 
int a[MAXN];
int last;
int count_sw, count_cmp;
 
//初始化测试数据
void init () {
	srand(time(0));
	//参与查询的数据
	for(int i=0; i<MAXN; ++i) {
		a[i] =  rand()%MAXN;
	}
	return ;
}
void swap(int &x, int &y) {
	int t ;
	t = x;
	x = y;
	y = t;
	return ;
}
 
void qsort(int arr[], int start, int end) {
	if(start < end) {
		int mid = arr[rand()%(end-start) + start];
		int i = start - 1;
		int j = end + 1;
		while (true) {
			while (arr[++i] > mid) count_cmp++;
			while (arr[--j] < mid) count_cmp++;
			if(i>=j) break;
			swap(arr[i], arr[j]);
			count_sw++;
		}
		qsort (arr, start, i-1);
		qsort (arr, j+1, end);
	}
	return ;
}
 
void topK(int arr[], int start, int end, int k) {
	if(start < end) {
		int mid = arr[rand()%(end-start) + start];
		int i = start - 1;
		int j = end + 1;
		while (true) {
			while (arr[++i] > mid) count_cmp++;
			while (arr[--j] < mid) count_cmp++;
			if(i>=j) break;
			swap(arr[i], arr[j]);
			count_sw++;
		}
		if(i-start > k) {
			last = i-1;
			topK (arr, start, i-1, k);
		} else{
			qsort(arr, start, last);
		}
	}
	return ;
}
 
int main() {
	init();
	count_sw = 0;
	count_cmp = 0;
	topK(c, 0, MAXN-1,10);
	cout << "Result:" << MAXN << endl;
	for(int i=0; i<10; ++i) {
		cout << c[i] << endl;
	}
	cout << "Swaps:" << count_sw << endl;
	cout << "Campare:" << count_cmp << endl;
	return 0;
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
 
namespace FTP_Search
{
    public partial class Form1 : Form
    {
        private void Upload(string filename)
        {
            FileInfo fileInf = new FileInfo(filename);
            string uri = "<a href="ftp://ftp.nuaa.edu.cn/">ftp://ftp.nuaa.edu.cn/</a>" + fileInf.Name;
            FtpWebRequest reqFTP;
 
            // 根据uri创建FtpWebRequest对象
            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
 
            // ftp用户名和密码
            reqFTP.Credentials = new NetworkCredential("nuaa", "nuaa");
 
            // 默认为true，连接不会被关闭
            // 在一个命令之后被执行
            reqFTP.KeepAlive = false;
 
            // 指定执行什么命令
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
 
            // 指定数据传输类型
            reqFTP.UseBinary = true;
 
            // 上传文件时通知服务器文件的大小
            reqFTP.ContentLength = fileInf.Length;
 
            // 缓冲大小设置为2kb
            int buffLength = 2048;
 
            byte[] buff = new byte[buffLength];
            int contentLen;
 
            // 打开一个文件流 (System.IO.FileStream) 去读上传的文件
            FileStream fs = fileInf.OpenRead();
            try
            {
                // 把上传的文件写入流
                Stream strm = reqFTP.GetRequestStream();
 
                // 每次读文件流的2kb
                contentLen = fs.Read(buff, 0, buffLength);
 
                // 流内容没有结束
                while (contentLen != 0)
                {
                    // 把内容从file stream 写入 upload stream
                    strm.Write(buff, 0, contentLen);
 
                    contentLen = fs.Read(buff, 0, buffLength);
                }
 
                // 关闭两个流
                strm.Close();
                fs.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Upload Error");
            }
        }
 
        private void Download(string filePath, string fileName)
        {
            FtpWebRequest reqFTP;
 
            try
            {
                FileStream outputStream = new FileStream(filePath + "" + fileName, FileMode.Create);
 
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("<a href="ftp://ftp.nuaa.edu.cn/">ftp://ftp.nuaa.edu.cn</a>"));
 
                reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
 
                reqFTP.UseBinary = true;
 
                reqFTP.Credentials = new NetworkCredential("nuaa", "nuaa");
 
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
 
                Stream ftpStream = response.GetResponseStream();
 
                long cl = response.ContentLength;
 
                int bufferSize = 2048;
 
                int readCount;
 
                byte[] buffer = new byte[bufferSize];
 
                readCount = ftpStream.Read(buffer, 0, bufferSize);
 
                while (readCount &gt; 0)
                {
                    outputStream.Write(buffer, 0, readCount);
 
                    readCount = ftpStream.Read(buffer, 0, bufferSize);
                }
 
                ftpStream.Close();
 
                outputStream.Close();
 
                response.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
 
        public string[] GetFileList()
        {
            string[] downloadFiles;
            StringBuilder result = new StringBuilder();
            FtpWebRequest reqFTP;
            try
            {
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("<a href="ftp://ftp2.nuaa.edu.cn/">ftp://ftp2.nuaa.edu.cn</a>"));
                reqFTP.UseBinary = true;
                reqFTP.Credentials = new NetworkCredential("nuaa", "nuaa");
                reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
                WebResponse response = reqFTP.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(),Encoding.GetEncoding("GB2312"));
                string line = reader.ReadLine();
                while (line != null)
                {
                    result.Append(line);
                    result.Append("n");
                    line = reader.ReadLine();
                }
                // to remove the trailing 'n'
                result.Remove(result.ToString().LastIndexOf('n'), 1);
                reader.Close();
                response.Close();
                return result.ToString().Split('n');
            }
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
                downloadFiles = null;
                return downloadFiles;
            }
        }
 
        public Form1()
        {
            InitializeComponent();
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            MessageBox.Show(GetFileList()[1]);
        }
    }
}

#include <iostream> 
#include <string> 
#include <cmath> 
#include <cstdlib>
 
using namespace std; 
 
const  double	PRECISION = 1E-6; 
const  int	COUNT_OF_NUMBER  = 4;  
const  int	NUMBER_TO_BE_CAL = 24; 
 
double	number[COUNT_OF_NUMBER]; 
string	expression[COUNT_OF_NUMBER]; 
bool	Judgement = false;	//判断是否有解。
int	count = 0;  
 
void Search(int n) 
{
	if (n==1) { 
		if (fabs(number[0] - NUMBER_TO_BE_CAL) <= PRECISION) {	//对于除法，要小心小数的精确位数  
			cout <<expression[0] <<"\t\t";  
			Judgement = true;
			++count;
			if((count % 3)==0)
				cout <<endl;
		} 
	} 
	for(int i=0; i < n; ++i) {
		for (int j=i+1; j<n; ++j) { 
			double	a, b; 
			string		expa, expb; 
 
			a = number[i]; 
			b = number[j]; 
			number[j]  =  number[n-1]; //递归之后，n比以前小一位，所以可以不停向前赋值  
 
			expa = expression[i]; 
			expb = expression[j]; 
			expression[j]  =  expression[n - 1]; //递归之后，n比以前小一位，所以可以不停向前赋值
 
			expression[i] = '(' + expa + '+' + expb + ')'; //加法不需要分顺序
			number[i] = a + b; 
			Search(n-1);
 
			expression[i] = '(' + expa + '-' + expb + ')'; //减法应该分顺序，减数以及被减数
			number[i] = a - b; 
			Search(n-1);  
 
			expression[i] = '(' + expb + '-' + expa + ')'; //减法应该分顺序，减数以及被减数
			number[i] = b - a; 
			Search(n-1);  
 
			expression[i] = '(' + expa + '*' + expb + ')'; //乘法不需要分顺序
			number[i] = a * b; 
			Search(n-1);  
 
			if (b != 0) { 
				expression[i] = '(' + expa + '/' + expb + ')'; //除法应该分顺序，除数以及被除数
			    number[i] = a / b; 
			    Search(n-1); 
			}   
			if (a != 0) { 
			    expression[i] = '(' + expb + '/' + expa + ')'; //除法应该分顺序，除数以及被除数
			    number[i] = b  /  a; 
			    Search(n-1); 
			} 
 
			number[i] = a;      //这4句语句是为了防止如果上面几种可能都失败了的话,
			number[j] = b;      //就把原来的赋值撤消回去,以无干扰的正确的进入到下一次
			expression[i] = expa;     //for循环队列中。
			expression[j] = expb;     
      } 
  } 
} 
 
 
int  main() 
{ 
	cout<<"输入四个数:\n";
	for (int i=0; i < COUNT_OF_NUMBER; ++i) { 
		char buffer[20];  
		cout <<"第"<<i+1<<"个数:";
		cin >>number[i];       
		itoa(number[i], buffer, 10);
		expression[i] = buffer; 
	} 
	cout <<endl;
	Search(COUNT_OF_NUMBER) ;
	if(Judgement){ 
		cout <<"\n成功" <<endl; 
		cout <<"求和方法有 " <<count <<" 种" <<endl;
	} 
	else { 
		cout << "失败" << endl; 
	}    
	return 0;
}