求质数

试编写一个程序,找出前N个质数.尽可能用最快的方法.

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#include <stdio.h>
#include <time.h>
#include <math.h>

#define PRIMEMAX    200

int main(void)
{
    double s,t;
    int prime[PRIMEMAX];
    int N = PRIMEMAX;
    int count = 0;
    int i = 2;
    int j = 2;
    s = clock();
    while(count<N)
    {
        if(i==2 || i==3 || i==5 || i==7)
        {
            printf("%d...",i);
            prime[count] = i;
            count++;
            i++;
            continue;
        }
        if(i%2==0){i++;continue;}
        if(i%3==0){i++;continue;}
        if(i%6==0){i++;continue;}
        if(i%5==0){i++;continue;}
        if(i%7==0){i++;continue;}
        for(j=0; j<count; j++)
        {
            if(i%prime[j] == 0)        //用质数去除来判断
            {
                i++;
                continue;
            }
        }
        printf("%d...",i);
        prime[count] = i;
        i++;
        count++;
    }
    t = clock();
    
    printf("\n-------time:%fms\n",t-s);

    return 0;
}