欧拉函数 || LightOJ 1370 Bi-shoe and Phi-shoe

#include <iostream>
#include <cstdio>
using namespace std;
#define SZ 1000005
long long phi[SZ], a[SZ];
void getphi(int n)
{
    for(int i = 2; i <= n; i++) phi[i] = 0;
    phi[1] = 0;
    for(long long i = 2; i <= n; i++)
    {
        if(!phi[i])
            for(long long j = i; j <= n; j += i)
            {
                if(!phi[j]) phi[j] = j;
                phi[j] = phi[j] / i * (i - 1);
            }
    }
}
int main()
{
    int T, cc = 0;
    scanf("%d", &T);
    phitable(SZ);
    while(T--)
    {
        int n;
        scanf("%d", &n);
        long long ans = 0;
        for(int i = 0; i < n; i++)
            scanf("%lld", &a[i]);
        sort(a, a+n);
        long long j = 0, i = 0;
        while(i < n)
        {
            if(a[i] > phi[j]) {j++; continue;}
            ans += j;
            i++;
        }
        printf("Case %d: %lld Xukha\n", ++cc, ans);
    }
    return 0;
}