Codeforces Round #412 C

Codeforces Round #412 C - Success Rate

算出最小倍数就可以了  

p要大于等于y

q要大于等于x

对于x增加 y也随增加

(y-x)*i<=(p-q)

#include <stdio.h>#include <bits/stdc++.h>#define read(); freopen("input.txt","r",stdin);using namespace std;typedef long long ll;int t;int gcd(int n,int m){if(n%m==0) return m;return gcd(m,n%m);}int main(){cin>>t;while(t--){ll x,y,p,q;cin>>x>>y>>p>>q;if(p/q==1){if(x/y==1)cout<<0<<endl;else cout<<-1<<endl;continue;}if(p==0){if(x==0)cout<<0<<endl;else cout<<-1<<endl;continue;}int k=gcd(p,q);p/=k;q/=k;ll ans=0;ll maxn= (y-x)/(q-p)+((y-x)%(q-p)?1:0);maxn=max(maxn,y/q+(y%q?1:0));maxn=max(maxn,x/p+(x%p?1:0));ans=q*maxn-y;cout<<ans<<endl; }return 0;}