#include "iostream.h"
#include "windows.h"
int searchprime(int num,int *out)
{
int pn=0;
long t1, t2;
bool *mask=new bool[num+1];
memset(mask, 0, sizeof(bool)*(num+1));
t1 = GetTickCount();
for(int i=2;i<=num;i++)
{
if(!mask[i])
{
out[pn++]=i;
if(i<32767)
for(int j=i*i;j<=num;j+=i)
mask[j]=true;
}
}
t2 = GetTickCount();
cout<<"用时:"<<t2 - t1<<"ms"<<endl;
delete []mask;
return pn;
}
void main()
{
//int *out=new int[664579];
int *out=new int[664579];
cout<<"搜索1 ~ 10000000......"<<endl;
int num=searchprime(10000000,out);
cout<<"找到"<<num<<"个素数,最后一个素数是"<<out[num-1]<<endl;
//for(int i=0;i<100;i++)
//{
// cout<<i<<":"<<out[i]<<endl;
//}
delete []out;
}
这个素数算法最初是在看雪上看到的,以前没想到过可以这样来求素数,非常经典,dwing的算法不错......
http://bbs.pediy.com/showthread.php?t=40052