Submission #1179176

#	Time	Username	Problem	Language	Result	Execution time	Memory
1179176		razivo	Portal (BOI24_portal)	C++20	21 / 100	42 ms	7240 KiB

Main

#include <iostream>
#include <vector>
using namespace std;
typedef pair<long long, long long> pt;
long long d(pt a, pt b) {
    return a.first*b.first+a.second*b.second;
}
long long det(pt a,pt b) {
    return a.first*b.second-a.second*b.first;
}
long long di(long long a, long long b) {
    if(a>0) return a/b;
    if(a==0) return 0;
    a = -a;
    if(a%b==0) return -(a/b);
    else return -(a/b) - 1;
}
int k = 0;
pt mod(pt a,pt b, pt c) {
    if(a.first<0) {a.first*=-1; a.second*=-1;}
    if(b.second<0) {b.first*=-1; b.second*=-1;}
    long long multb = di(d(b,c),(b.first*b.first+b.second*b.second));
    long long multa = di(d(a,c),(a.first*a.first+a.second*a.second));
    return {c.first-b.first*multb-a.first*multa,c.second-b.second*multb-a.second*multa};
}
pt d1red(pt a,pt b) {
    if(a.first<0) {a.first*=-1; a.second*=-1;}
    if(b.first<0) {b.first*=-1; b.second*=-1;}
    pt p = {0,0};
    long long mult = di(d(a,b),(a.first*a.first+a.second*a.second));
    b = {b.first-a.first*mult,b.second-a.second*mult};
    if(b==a) return a;
    if(b==p) return a;
    return d1red(b,a);
}
pair<pt,pt> reduce(pt a, pt b, pt c) {
    k++;
    if(k>50000) return {a,c};
    if(a.first<0) {a.first*=-1; a.second*=-1;}
    if(b.first<0) {b.first*=-1; b.second*=-1;}
    pt p = {0,0};
    if(a==p ||b==p||c==p) exit(1);
    if(det(a,b)==0) {
        k=0;
        return {
            d1red(a,b),c};
    }
    c = mod(a,b,c);
    if(c==a) return {c,b};
    else if(c==b) return {c,a};
    if(c == p) return {a,b};
    return reduce(b,c,a);
}
int main() {
    int n; cin>>n;
    if(n<3) {
        cout<<-1<<endl;
        return 0;
    }
    pt prev;
    cin>>prev.first>>prev.second;
    vector<pt> t(n-1);
    for (int i = 0; i < n-1; ++i) {
        int x,y; cin>>x>>y;
        t[i] = {prev.first-x,prev.second-y};
        prev = {x,y};
    }
    pair<pt,pt> res = {t[0],t[1]};
    for (int i = 0; i < n-3; ++i) {
        k=0;
        res = reduce(res.first,res.second,t[i+2]);
    }
    pt p = {0,0};
    if(res.first==res.second || res.first==p || res.second==p|| det(res.first,res.second)==0) {
        cout<<-1<<endl;
        return 0;
    }else {
        cout<<abs(res.first.first*res.second.second-res.first.second*res.second.first)<<endl;
        return 0;
    }
}

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