POJ 3090 (欧拉函数) Visible Lattice Points

UVa 10820

#include <cstdio>

const int maxn = 1000;
int phi[maxn + 10];

void get_table()
{
for(int i = 2; i <= maxn; ++i) if(!phi[i])
{
for(int j = i; j <= maxn; j += i)
{
if(!phi[j]) phi[j] = j;
phi[j] = phi[j] / i * (i - 1);
}
}
}

int main()
{
freopen("3090in.txt", "r", stdin);

get_table();
for(int i = 1; i <= maxn; ++i) phi[i] += phi[i - 1];

int T;
scanf("%d", &T);
for(int kase = 1; kase <= T; ++kase)
{
int n;
scanf("%d", &n);
printf("%d %d %d\n", kase, n, phi
*2+3);
}

return 0;
}