查询 CF 评测机速度

#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
int T,x,y,k;
int check(int mid){
	for(int t=x;t;){
		int a=mid/y;
		if(a==0) return mid;
		if(t<=1e6){
			mid-=a,--t;
			continue;
		}
		int b=mid%y,w=b/a+1;
		if(t>=mid-(y-1)) return y-1;
		if(t<w) return mid-a*t;
		t-=w,mid-=a*w;
	}
	return mid;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	cin>>T;
	while(T--){
		cin>>x>>y>>k;
		int l=k,r=1e12;
		if(check(r)<k){
			cout<<-1<<endl;
			continue;
		}
		while(l<r){
			int mid=l+r>>1;
			if(check(mid)>=k) r=mid;
			else l=mid+1;
		}
		cout<<r<<endl; 
	}
	return 0;
}