UVa 10325 - The Lottery

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=15&problem=1266&mosmsg=Submission+received+with+ID+11830997

容斥原理 第一题  水！

代码：

#include<iostream>
#include<cstring>
#include<cstdio>
#include<string>
#include<set>
#include<map>
#include<cmath>
#include<algorithm>
#include<vector>
#include<cmath>
#include<queue>
#include<stack>

//#define ull unsigned long long
#define ll long long

using namespace std;

const int INF=0x3f3f3f3f;
const int MOD=1000000007;
const double eps=1e-6;
const int N=50;
ll gcd(ll x,ll y)
{
    if(x%y==0)
    return y;
    return gcd(y,x%y);
}
ll lcm(ll x,ll y)
{
    return x*y/gcd(x,y);
}
ll a[N];
ll solve(ll *a,int n,ll M)
{
    ll sum=0;
    for(int k=1;k<(1<<n);++k)
    {
        ll LCM=1;
        int num=0;
        for(int i=0;i<n;++i)
        {
            if(k&(1<<i))
            {
                ++num;
                LCM=lcm(LCM,a[i]);
            }
        }
        if((num&1)==1)
        {
            sum+=(M/LCM);
        }else
        {
            sum-=(M/LCM);
        }
    }
    return sum;
}
int main()
{
    //freopen("data.in","r",stdin);
    ll n;
    int m;
    while(cin>>n>>m)
    {
        for(int i=0;i<m;++i)
        cin>>a[i];
        cout<<(n-solve(a,m,n))<<endl;
    }
    return 0;
}