xtu oj 1355

include<stdio.h>
#define N 3000005
int z[N]={0};//0是质数 
__int64 phi[N]={0};
__int64 sum[N]={0};
int main( )
{
    __int64 i,j;
    z[1]=1;
    for(i=2;i<=N;i++)
    {
        for(j=i*i;j<=N;j+=i)
        {
            z[j]=1;
        }
    }
    phi[1]=1;
    for(i=2;i<=N;i++)
    {
        if(z[i]==1)
        {
            phi[i]=i;
        }
        else
        {
            phi[i]=i-1;
        }
    }
//    printf("=-=%d\n",z[2]);
//        printf("%I64d\n",phi[2]);
    for(i=2;i<=N;i++)
    {
        if(z[i]==0)
        {
            for(j=2;j*i<=N;j++)
            {
                phi[i*j]=phi[i*j]*phi[i]/i;
            }
        }
    }
//        printf("%I64d\n",phi[2]);
    for(i=1;i<=N;i++)
    {
        sum[i]=sum[i-1]+phi[i];
    }
    int T;
//    printf("%I64d\n",phi[2]);
    scanf("%d",&T);
    while(T--)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        printf("%I64d\n",sum[b]-sum[a]+phi[a]);
    }
}

Memory: 59980K Time: 968MS
Language: G++ Result: Accepted

标签：__,phi,oj,int,sum,xtu,1355,printf,I64d
来源： https://blog.csdn.net/TheShine912/article/details/111059494