primepro.cpp

几个实用算法:质数 组合数 公约数 字符串长度

/*
  Name: 
  Copyright: Seu.Edu.Cn
  Author: ufouser
  Id: 09002611
  Date: 
  Description:    			
  
*/


#include <iostream>
#include <cstdlib>
#include <ctime>
#include <memory>
#include <cmath>
using namespace std;

const long MAXSIZE = 100;
bool isPrime[MAXSIZE + 1];


int main()
{
	
	memset(isPrime,1,sizeof(isPrime));
	isPrime[0] = isPrime[1] = false;
	double sqrtMax = sqrt(double(MAXSIZE));
	
	for (long i = 2; i <= sqrtMax; ++i)
	{
		if (isPrime[i])
		{
			double MAXDi = double(MAXSIZE) / i;
			for (long j = i; j <= MAXDi; ++j)
			{
				if (isPrime[j])
				{
					isPrime[i*j] = false;
				}
    		}
    	}
     }
     long count = 0;
     
     for (long i = 2; 	i < MAXSIZE; ++i)
     {
     	if (isPrime[i])
     	{
     		cout << i << ' ';
     		count++;
     	}
     }
     cout << endl << "Total=" << count << endl; 	
    
    system("PAUSE");	
    return 0;
}