L1-009 N个数求和 (20 分)

 这题我傻了。。

#include 
#include 
using namespace std;
typedef long long LL;
int n;

void merge(LL &a1, LL &b1, LL &a2, LL &b2)
{
    LL fenmu = (b1 * b2) / __gcd(b1, b2);
    LL fenzi = (fenmu / b1) * a1 + (fenmu / b2) * a2;
    a1 = fenzi, b1 = fenmu;
}
int main()
{
    LL a1, b1, a2, b2;
    char ch;
    cin >> n;
    cin >> a1 >> ch >> b1;
    for(int i = 0; i < n -1; i++)
    {
        cin >> a2 >> ch >> b2;
        merge(a1, b1, a2, b2);
    }
    
    LL k = __gcd(a1, b1);
    a1 /= k;
    b1 /= k;
    if(a1 && a1 / b1 == 0) cout << a1 << "/" << b1;
    else if(a1 % b1 == 0) cout << a1 / b1 << endl;
    else cout << a1/b1 << ' ' << a1 % b1 << "/" << b1;
    return 0;
}