program.cs

用近似算法计算最大选择数

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Collections;

 
namespace selectionMax
{
   
    class Program
    {
        public const int Num = 10000;
        public int[] data = new int[Num];
        public  void  generateData()
        {
            StreamWriter sw = new StreamWriter("data.txt");
            
            Random ra = new Random();
            for (int i = 0; i < Num; i++)
                data[i] = ra.Next();
            for (int i = 0; i < Num; i++)
                sw.WriteLine(data[i]);
            sw.Close();
            

        }
        public  void quicksotr( int first, int last)
        {
            
            int pos =0;
            int bigin = 0;
            if (first < last)
            {
                while (pos != 17)
                {
                    pos = split(first, last);
                    first++;
                    swap(bigin, first);
                    if (first == last)
                        break;
                }
              //   quicksotr(first,pos-1);
               // quicksotr(pos + 1, last);
              
                Console.WriteLine(pos.ToString()+"\t"+first.ToString());
            }


        }
        public int split( int first, int last)
        {
            int pivot = data[first];
            int left = 0;
            int right = last;
            while (left < right)
            {
                while (pivot < data[right])
                    right--;
                while (left < right && pivot > data[left] || data[left] == pivot)
                    left++;
                if (left < right)
                    swap(left, right);
            }
            int pos = right;
            data[first] = data[pos];
            data[pos] = pivot;
            return pos;
        }
        void swap(int left, int right)
        {
            int temp;
            temp = data[left];
            data[left] = data[right];
            data[right] = temp;
        }

        void testSlect()
        {
 
        }
        static void Main(string[] args)
        {
            DateTime dt = DateTime.Now;
            int count = 0;
            StreamWriter sw = new StreamWriter("result.txt");
            Program sl = new Program();
            while (count < 1)
            {
                count++;
                sl.generateData();
                int len = sl.data.Length;
                sl.quicksotr(0, len - 1);
              
                for (int i = 0; i < Num; i++)

                    sw.WriteLine(sl.data[i]);
                sw.WriteLine("this is another data");
                //sw = File.Create("data.txt");
                 
            }
            DateTime du = DateTime.Now;
            Console.WriteLine("use m for second{0:%s}",du-dt);
            sw.Close();

        }
    }
}