Submission #1012463

#	Time	Username	Problem	Language	Result	Execution time	Memory
1012463		ttamx	Portal (BOI24_portal)	C++17	1 / 100	58 ms	10804 KiB

Main

#include<bits/stdc++.h>

using namespace std;

using ll = long long;

const int N=1e5+5;

int n;
int piv;
ll x[N],y[N];
map<ll,ll> pre;
map<pair<ll,ll>,pair<ll,ll>> mp;

int main(){
    cin.tie(nullptr)->sync_with_stdio(false);
    cin >> n;
    for(int i=1;i<=n;i++){
        cin >> x[i] >> y[i];
        if(pre.count(x[i])){
            if(pre[x[i]]!=y[i])piv=i;
        }else{
            pre[x[i]]=y[i];
            piv=i;
        }
    }
    for(int i=1;i<=n;i++)if(i!=piv){
        ll dx=x[i]-x[piv],dy=y[i]-y[piv];
        ll g=gcd(dx,dy);
        if(dx<0)dx=-dx,dy=-dy;
        if(dx==0)dy=abs(dy);
        pair<ll,ll> m(dx/g,dy/g);
        if(mp.count(m)){
            mp[m].first=gcd(mp[m].first,dx);
            mp[m].second=gcd(mp[m].second,dy);
        }else{
            mp[m]={dx,dy};
        }
    }
    if(mp.size()<2)cout << -1,exit(0);
    auto [x1,y1]=mp.begin()->second;
    ll ans=0;
    for(auto [m,v]:mp){
        auto [x2,y2]=v;
        if(x1==x2&&y1==y2)continue;
        ll c=x1*y2-x2*y1;
        ll d=y2/gcd(y1,y2);
        ll e=c*d;
        ll g=gcd(e,y2);
        ans=gcd(ans,e/g);
    }
    cout << ans;
}

• Subtask 1: 1 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 29
• Subtask 5: 0 / 15
• Subtask 6: 0 / 35