#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,now1=0,now2=1;
main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		int x,y,z,d;
		cin>>x>>y>>z;
		d=__gcd(y,now2);
		now1*=y/d;
		if(z==1)now1-=x*now2/d;
		else now1+=x*now2/d;
		now2=now2*y/d;
	}
	int d=__gcd(now1,now2);
	now1/=d,now2/=d;
	if(now2<0)now2=-now2;else now1=-now1;
	if(now2==1){
		cout<<now1;
	}else{
		cout<<now1<<"/"<<now2;
	}
}

？？？

if(now2<0)now2=-now2;else now1=-now1;

为啥加了这个才A了?