Submission #481203

#	Time	Username	Problem	Language	Result	Execution time	Memory
481203		hidden1	Triangles (CEOI18_tri)	C++14	100 / 100	25 ms	2956 KiB

tri

#include <bits/stdc++.h>

#include "trilib.h"

using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#ifndef LOCAL
#define cerr if(false) cerr
#endif
#define endl "\n"
#define all(x) (x).begin(), (x).end()
#define forn(i, n) for(int i = 0; i < n; i ++)
#define revn(i, n) for(int i = n - 1; i >= 0; i --)
typedef long long ll;
template<class T, template<class T2, class A=allocator<T2> > class cont> inline ostream &operator <<(ostream &out, const cont<T> &x) { for(const auto &it : x) { out << it << " ";} return out;}
template<class T, template<class T2, class A=allocator<T2> > class cont> inline istream &operator >>(istream &in, cont<T> &x) { for(auto &it : x) { in >> it;} return in;}
template<class T, class T2> inline ostream &operator <<(ostream &out, const pair<T, T2> &x) { out << x.first << " " << x.second; return out;}
template<class T, class T2> inline istream &operator >>(istream &in, pair<T, T2> &x) { in >> x.first >> x.second; return in;}
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;

signed main() {
    // ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

    int n;
    int special = 1;
    n = get_n();

    vector<int> vert1, vert2;
    forn(i, n) {
        if(i != 0 && i != 1) {
            if(is_clockwise(1, 2, i + 1)) {
                vert1.push_back(i + 1);
            } else {
                vert2.push_back(i + 1);
            }
        }
    }

    sort(all(vert1), [&special](const int a, const int b) {
        return (bool)!is_clockwise(1, a, b);
    });

    sort(all(vert2), [&special](const int a, const int b) {
        return (bool)!is_clockwise(1, a, b);
    });

    vector<int> vert;
    vert.push_back(1);
    for(auto it : vert1) {vert.push_back(it);}
    vert.push_back(2);
    for(auto it : vert2) {vert.push_back(it);}

    vector<int> st;

    for(auto it : vert) {
        while(!(st.size() < 2) && is_clockwise(st[st.size() - 2], st[st.size() - 1], it)) {
            st.pop_back();
        }
        st.push_back(it);
    }

    int ret = st.size();

    auto cpy = st;
    for(auto it : cpy) {
        while(!(st.size() < 2) && is_clockwise(st[st.size() - 2], st[st.size() - 1], it)) {
            st.pop_back();
            ret --;
        }
        st.push_back(it);
    }

    give_answer(ret);

    return 0;
}

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