HDU 5768 Lucky7

中国剩余定理+容斥原理。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-8;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
inline int read()
{
    char c = getchar();  while(!isdigit(c)) c = getchar();
    int x = 0;
    while(isdigit(c)) { x = x * 10 + c - '0'; c = getchar(); }
    return x;
}

const int maxn=20;
int T,p,cas=1,limit;
LL L,R,A[maxn],B[maxn],h,a[maxn],b[maxn];

LL Extend_Euclid(LL a, LL b, LL&x, LL& y)
{
    if(b==0)
    {
        x=1,y=0;
        return a;
    }
    LL d = Extend_Euclid(b,a%b,x,y);
    LL t = x;
    x = y;
    y = t - a/b*y;
    return d;
}

LL China_Reminder(int len, LL* a, LL* n)
{
    int i;
    LL N = 1;
    LL result = 0;
    for(i = 0; i < len; i++) N = N*n[i];
    for(i = 0; i < len; i++)
    {
        LL m = N/n[i];
        LL x,y;
        Extend_Euclid(m,n[i],x,y);
        x = (x%n[i]+n[i])%n[i];
        result = (result + m*a[i]*x%N)%N;
    }
    return result;
}

void dfs(int x,int s)
{
    if(s==limit)
    {
        a[s]=7, b[s]=0;
        LL res=China_Reminder(s+1,b,a); if(res>R) return;
        LL rep=1; for(int i=0;i<=s;i++) rep*=a[i];
        LL small,large;
        if(res>=L) small=0; else small=(L-res)%rep==0 ? ((L-res)/rep):((L-res)/rep+1);
        large=(R-res)/rep;
        h=h+large-small+1;
        return;
    }
    if(x==p+1) return;
    dfs(x+1,s);
    a[s]=A[x], b[s]=B[x]; dfs(x+1,s+1);
}

int main()
{
    scanf("%d",&T); while(T--)
    {
        scanf("%d%lld%lld",&p,&L,&R);
        for(int i=1;i<=p;i++) scanf("%lld%lld",&A[i],&B[i]);
        LL sum=0,f=1;
        for(int i=1;i<=p;i++) limit=i, h=0, dfs(1,0), sum=sum+f*h, f=-f;
        printf("Case #%d: %lld\n",cas++,R/7-(L-1)/7-sum);
    }
    return 0;
}