Submission #47521

#	Time	Username	Problem	Language	Result	Execution time	Memory
47521		qoo2p5	Fences (JOI18_fences)	C++17	0 / 100	2 ms	536 KiB

fences

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;

#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define mp make_pair
#define pb push_back

bool mini(auto &x, const auto &y) {
    if (y < x) {
        x = y;
        return 1;
    }
    return 0;
}

bool maxi(auto &x, const auto &y) {
    if (y > x) {
        x = y;
        return 1;
    }
    return 0;
}

void run();

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    run();
    return 0;
}

typedef long double ld;

struct Vect {
    ll x, y;
    
    Vect() : x(0), y(0) {}
    
    Vect(ll x, ll y) : x(x), y(y) {}
    
    Vect(const Vect &a, const Vect &b) : x(b.x - a.x), y(b.y - a.y) {}
    
    Vect operator+(const Vect &b) const {
        return Vect(x + b.x, y + b.y);
    }
    
    bool operator==(const Vect &b) const {
        return mp(x, y) == mp(b.x, b.y);
    }
    
    ld len() const {
        return hypot(x, y);
    }
    
    ll operator*(const Vect &b) {
        return x * b.y - b.x * y;
    }
    
    ll len2() const {
        return x * x + y * y;
    }
};

const int N = 101;

int n;
Vect a[N], b[N];
ll s;

vector<Vect> convex(vector<Vect> p) {
    Vect start = *min_element(all(p), [] (auto &x, auto &y) {
        return mp(x.x, x.y) < mp(y.x, y.y);
    });
    sort(all(p), [&] (auto &x, auto &y) {
        Vect u = Vect(start, x);
        Vect v = Vect(start, y);
        if (u * v > 0) {
            return true;
        }
        if (u * v < 0) {
            return false;
        }
        return u.len2() < v.len2();
    });
    vector<Vect> st;
    for (auto &v : p) {
        while (sz(st) >= 2 && Vect(st[sz(st) - 2], st[sz(st) - 1]) * Vect(st[sz(st) - 1], v) <= 0) {
            st.pop_back();
        }
        st.pb(v);
    }
    return st;
}

bool test(int mask, int bit) {
    return mask & (1 << bit);
}

void run() {
    cin >> n >> s;
    rep(i, 0, n) {
        cin >> a[i].x >> a[i].y >> b[i].x >> b[i].y;
    }
    
    ld ans = 8 * s;
    vector<Vect> p = {{s, s}, {s, -s}, {-s, -s}, {-s, s}};
    
    rep(mask, 0, 1 << n) {
        ld cur = 0;
        
        vector<Vect> tmp = p;
        rep(i, 0, n) {
            if (test(mask, i)) {
                tmp.pb(a[i]);
                tmp.pb(b[i]);
            }
        }
        tmp = convex(tmp);
        tmp.pb(tmp[0]);
        rep(i, 0, sz(tmp) - 1) {
            Vect x = tmp[i];
            Vect y = tmp[i + 1];
            ld cost = Vect(x, y).len();
            rep(j, 0, n) {
                if (!test(mask, j)) {
                    continue;
                }
                if (mp(x, y) == mp(a[j], b[j]) || mp(x, y) == mp(b[j], a[j])) {
                    cost = 0;
                }
            }
            cur += cost;
        }
        
        mini(ans, cur);
    }
    
    cout << fixed << setprecision(10) << ans << "\n";
}

• Subtask 1: 0 / 18
• Subtask 2: 0 / 33
• Subtask 3: 0 / 49