2019-03-10 分数求和

#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
const int maxn = 100;
int x[maxn],y[maxn];
int Gcd(int m,int n)
{
    if(m<n) return Gcd(n,m);
    return m%n==0?n:Gcd(n,m%n);
}
int Lcm(int m,int n)
{
    return m*n/Gcd(m,n); 
}
int main(void)
{
    int n;
    cin >> n;
    int lcm=1,gcd,sum=0;
    for(int i=0;i<n;i++)
    {
        cin>>x[i]>>y[i];
        lcm=Lcm(lcm,y[i]);
        sum+=x[i]*(y[i]/x[i]);
    }
    gcd=Gcd(lcm,sum);
    int xx=sum/gcd;
    int yy=lcm/gcd;
    printf("%d/%d",xx,yy);
    return 0;
}