HDU 4135 Co-prime(组合+容斥）

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<string>
#include<iostream>
#include<queue>
#include<cmath>
#include<map>
#include<stack>
#include<bitset>
using namespace std;
#define REPF( i , a , b ) for ( int i = a ; i <= b ; ++ i )
#define REP( i , n ) for ( int i = 0 ; i < n ; ++ i )
#define CLEAR( a , x ) memset ( a , x , sizeof a )
typedef long long LL;
typedef pair<int,int>pil;
const int mod = 1000000007;
LL a,b,n;
int t;
LL solve(LL r,LL n)
{
    vector<int>v;
    for(int i=2;i*i<=n;i++)
    {
        if(n&&n%i==0)
        {
            v.push_back(i);
            while(n&&n%i==0)
                n/=i;
        }
    }
    if(n>1)  v.push_back(n);
    LL sum=0;
    for(int t=1;t<(1<<v.size());t++)
    {
        LL mul=1,bits=0;
        for(int i=0;i<(int)v.size();i++)
        {
            if(t&(1<<i))
            {
                ++bits;
                mul*=v[i];
            }
        }
        if(bits&1)  sum+=r/mul;
        else   sum-=r/mul;
    }
    return r-sum;
}
int main()
{
    int cas=1;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%I64d%I64d%I64d",&a,&b,&n);
        printf("Case #%d: %I64d\n",cas++,solve(b,n)-solve(a-1,n));
    }
    return 0;
}