1e9个兵临城下

https://ac.nowcoder.com/acm/contest/321#question

代码写得蛮丑的。。真的很丑

像是高中教的veen图，并涉及到容斥原理。

 #include<cstdio>
 #include<cmath>
 #include<cstring>
 #include<iostream>
 #include<algorithm>
 #include<bits/stdc++.h>
 using namespace std;
 #define mem(a) memset(a,0,sizeof(a))
 #define ll long long
 #define maxx 1e9
 ll gcd(ll a,ll k)
 {
     if(k == )
         return a;
     else
         return gcd(k,a%k);
 }

 int main()
 {
     int t;
     cin>>t;
     while(t--)
     {
         ll a,b,c,u=maxx;
         cin>>a>>b>>c;
        ll cnt=;
        ll m,n,p;
        m=a/gcd(a,b)*b;
        n=a/gcd(a,c)*c;
        p=b/gcd(b,c)*c;
        cnt=cnt/gcd(cnt,a)*a;
        cnt=cnt/gcd(cnt,b)*b;
        cnt=cnt/gcd(cnt,c)*c;
        u=u-(u/a+u/b+u/c-u/m-u/n-u/p+u/cnt);
       cout<<u<<endl;
     }

 }