线性筛资料

贾志鹏ppt https://wenku.baidu.com/view/2d706761aa00b52acec7ca63.html

一个证明 http://blog.csdn.net/zmoiynlp/article/details/44566631

一个介绍http://blog.csdn.net/qingshui23/article/details/50969344

自写筛欧拉函数

        phi[1]=1;
    for (unsigned int i=2; i<N; i++){
        if (!phi[i]) p[pnum++]=i,phi[i]=i-1;
        for (unsigned int j=0; j<pnum&&p[j]*i<N; j++){
            if (i%p[j]==0){
                phi[i*p[j]]=phi[i]*p[j];
                break;
            }
            phi[i*p[j]]=phi[i]*phi[p[j]];
        }
    }