Submission #1039220

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039220		slivajan	Triangles (CEOI18_tri)	C++17	20 / 100	1 ms	760 KiB

tri

#include "trilib.h"

#include <bits/stdc++.h>
using namespace std;

typedef long long un;
typedef vector<un> vuc;
typedef set<un> sun;

#define vec vector
#define REP(i, a, b) for (un i = (un)a; i < (un)b; i++)
#define FEAC(i, a) for (auto&& i : a)
#define ALL(x) (x).begin(), (x).end()

un N;
vuc horni;
vuc dolni;
vuc cely;
vuc obal;

int main(){
    N = get_n();
    // if (N == 3){
    //     give_answer(3);
    //     return 0;
    // }

    REP(i, 3, N+1){
        if (not is_clockwise(1, 2, i)) horni.push_back(i);
        else dolni.push_back(i);
    }

    horni.push_back(2);
    dolni.push_back(2);

    sort(ALL(horni), [](un x, un y){return is_clockwise(1, x, y); });
    sort(ALL(dolni), [](un x, un y){return is_clockwise(1, x, y); });

    FEAC(a, horni) cely.push_back(a);
    cely.pop_back();
    FEAC(a, dolni) cely.push_back(a);

    obal.push_back(1);
    FEAC(a, cely){
        while((obal.size() != 1) and (not is_clockwise(obal[obal.size()-2], obal[obal.size()-1], a))){
            obal.pop_back();
        }
        obal.push_back(a);
    }

    un ign = 0;

    while (not is_clockwise(obal[obal.size()-1], obal[ign], obal[ign+1]))
    {
        ign++;
    }
    

    give_answer(obal.size()-ign);
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 20 / 20
• Subtask 5: 0 / 25