답안 #518265

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
518265 2022-01-23T09:28:41 Z kartel Geometrija (COCI21_geometrija) C++17
0 / 110
1 ms 204 KB
#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define F first
#define S second
#define sz(x) (int)x.size()
#define el "\n"
#define pi (ld)acos(-1.0)
//#pragma GCC target("avx2")
//#pragma GCC optimize("-O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef long double ld;

const int N = 1e3 + 500;

int n;
int x[N], y[N];

int sg(ll x) {
    if (x < 0) {
        return 0;
    }
    return 1;
}

ll det(ll a, ll b, ll c, ll d) {
    return (a * d - b * c);
}

ld to_degrees(ld x) {
    return x * ld(180) / pi;
}

ld get_alpha(ld a, ld b, ld c) {
//    cerr << acos((a + b - c) / (2.0 * sqrt((ld)a) * sqrt((ld)b))) << el;
    return to_degrees(acos((a + b - c) / (2.0 * sqrt((ld)a) * sqrt((ld)b))));
}

ll dist(ll a, ll b, ll c, ll d) {
    return ((a - c) * (a - c) + (b - d) * (b - d));
}

vector <pair <ld, ld> > vc[2];
ld sf[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
//    cerr.precision(10);
//    cerr << fixed;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i];
    }

    int ans = 0;
    for (int a = 0; a < n; a++) {
        for (int b = a + 1; b < n; b++) {
            vector <int> emp;
            for (int i = 0; i < n; i++) {
                if (i != a && i != b) {
                    emp.pb(i);
                }
            }
            bool bad = 0;
            for (int i = 0; i < n - 2 && !bad; i++) {
                int c = emp[i];
                for (int j = i + 1; j < n - 2 && !bad; j++) {
                    int d = emp[j];
                    int s1 = sg(det(x[b] - x[c], y[b] - y[c], x[d] - x[c], y[d] - y[c]));
                    int s2 = sg(det(x[d] - x[b], y[d] - y[b], x[a] - x[b], y[a] - y[b]));
                    int s3 = sg(det(x[a] - x[d], y[a] - y[d], x[c] - x[d], y[c] - y[d]));
                    if (s1 == s2 && s1 == s3) {
                        bad = 1;
                        break;
                    }
                }
            }
            if (!bad) {
                ans++;
            }
        }
    }
//    for (int a = 0; a < n; a++) {
//        for (int b = a + 1; b < n; b++) {
//            vc[0].clear(); vc[1].clear();
//            for (int c = 0; c < n; c++) {
//                if (a == c || b == c) {
//                    continue;
//                }
//                int sgn = sg(det(x[b] - x[a], y[b] - y[a], x[c] - x[a], y[c] - y[a]));
//                ll ab = dist(x[a], y[a], x[b], y[b]);
//                ll ac = dist(x[a], y[a], x[c], y[c]);
//                ll bc = dist(x[b], y[b], x[c], y[c]);
//                vc[sgn].pb({get_alpha(ab, bc, ac), get_alpha(ac, ab, bc)});
//            }
//
//            sort(all(vc[0]),
//                 [&](pair <ld, ld> a, pair <ld, ld> b) {
//                    return a.F > b.F;
//                 });
//            sort(all(vc[1]),
//                 [&](pair <ld, ld> a, pair <ld, ld> b) {
//                    return a.F < b.F;
//                 });
//
//            sf[sz(vc[0])] = 1e9;
//            for (int j = sz(vc[0]) - 1; j >= 0; j--) {
//                sf[j] = min(sf[j + 1], vc[0][j].S);
//            }
//            int i = 0;
//            bool bad = 0;
//            for (auto p : vc[1]) {
//                ld alpha = p.F;
//                ld beta = p.S;
//                while (i < sz(vc[0]) && alpha + vc[0][i].F > 180) {
//                    i++;
//                }
//                if (sf[i] + beta < 180.0) {
//                    bad = 1;
//                    break;
//                }
//            }
//            if (!bad) {
//                ans++;
//            }
//        }
//    }
    cout << ans;
}
# 결과 실행 시간 메모리 Grader output
1 Incorrect 1 ms 204 KB Output isn't correct
2 Halted 0 ms 0 KB -
# 결과 실행 시간 메모리 Grader output
1 Incorrect 1 ms 204 KB Output isn't correct
2 Halted 0 ms 0 KB -
# 결과 실행 시간 메모리 Grader output
1 Incorrect 1 ms 204 KB Output isn't correct
2 Halted 0 ms 0 KB -