hdu1164Eddy's research I

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1164

素数筛了。

代码:
#include <cstdio>

int prime[1000000];

void init()

{
    for(int i = 2;i <= 65535;++i)
        prime[i] = 1;

    for(int i = 2;i <= 65535;++i)
    {
        if(prime[i])
        {
            for(int j = 2 * i;j <= 65535;j += i)
                prime[j] = 0;
        }
    }
}

int nextPrime(int n)

{
    for(int i = n + 1;;++i)
        if(prime[i])
            return i;
}
int main()

{
    init();
    int n;
    while(~scanf("%d",&n))
    {
        if(prime[n])
        {
           printf("%d\n",n);
        }
        else
        {
            int cnt = 0;
            int t = 2;
            while(n!= 1)
            {
                if(n % t == 0)
                {
                    if(!cnt)
                        printf("%d",t);
                    else
                        printf("*%d",t);
                    n /= t;
                    //printf("%d ",n);
                    cnt++;
                }
                else t = nextPrime(t);
            }
            printf("\n");
        }
    }
}

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