Submission #1149761

#	Time	Username	Problem	Language	Result	Execution time	Memory
1149761		Zero_OP	Relay (COI16_relay)	C++20	0 / 100	9 ms	328 KiB

relay

#include <bits/stdc++.h>

using namespace std;

#define FOR(i, l, r) for(int i = (l); i < (r); ++i)
#define ROF(i, l, r) for(int i = (l) - 1; i >= (r); --i)

#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define sz(v) (int)v.size()
#define sum_of(v) accumulate(all(v), 0ll)
#define pb push_back
#define eb emplace_back
#define compact(v) v.erase(unique(all(v)), end(v))

#define dbg(x) "[" #x " = " << (x) << "]"
#define file(task) if(fopen(task".inp", "r")){ \
                        freopen(task".inp", "r", stdin); \
                        freopen(task".out", "w", stdout); }

template<typename T>
bool minimize(T& a, const T& b){
    if(a > b) return a = b, true;
    return false;
}

template<typename T>
bool maximize(T& a, const T& b){
    if(a < b) return a = b, true;
    return false;
}

using ll = long long;
using db = double;
using ld = long double;
using ull = unsigned long long;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;

using vi = vector<int>;
using vb = vector<bool>;
using vd = vector<db>;
using vpi = vector<pi>;
using vpl = vector<pl>;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

struct point{
    ll x, y;
    point() : x(0), y(0) {}
    point(ll x, ll y) : x(x), y(y){ }

    point& operator += (const point& o){
        x += o.x; y += o.y;
        return *this;
    }

    point& operator -= (const point& o){
        x -= o.x; y -= o.y;
        return *this;
    }

    point& operator *= (const ll& o){
        x *= o; y *= o;
        return *this;
    }

    point& operator /= (const ll& o){
        x /= o; y /= o;
        return *this;
    }

    friend point operator + (point a, const point& b){ return a += b; }
    friend point operator - (point a, const point& b){ return a -= b; }
    friend point operator * (point a, const ll& b){ return a *= b; }
    friend point operator / (point a, const ll& b){ return a /= b; }

    friend bool operator == (const point& a, const point& b){ return a.x == b.x && a.y == b.y; }
    friend bool operator != (const point& a, const point& b){ return a.x != b.x || a.y != b.y; }

    friend istream& operator >> (istream& in, point& o){ return in >> o.x >> o.y; }
    friend ostream& operator << (ostream& out, const point& o){ return out << '(' << o.x << ',' << o.y << ')'; }

    bool operator < (const point& o){ return make_pair(x, y) < make_pair(o.x, o.y); }
};

ll cross(const point& a, const point& b){
    return a.x * b.y - a.y * b.x;
}

ll cross3(const point& a, point b, point c){
    return cross(b - a, c - a);
}

ll dot(const point& a, const point& b){
    return a.x * b.x + a.y * b.y;
}

ll dot3(const point& a, point b, point c){
    return dot(b - a, c - a);
}

int sign(ll x){
    if(x < 0) return -1;
    if(x > 0) return +1;
    return 0;
}

bool point_on_segment(const point& a, const point& b, const point& c){ //C on AB
    return cross3(a, b, c) == 0 && dot3(c, a, b) <= 0;
}

bool intersect_two_segments(const point& a, const point& b, const point& c, const point& d, bool strictly){
    if(!strictly)
        if(point_on_segment(a, b, c) || point_on_segment(a, b, d) || point_on_segment(c, d, a) || point_on_segment(c, d, b)) return true;
    return sign(cross3(a, b, c)) * sign(cross3(a, b, d)) < 0 && sign(cross3(c, d, a)) * sign(cross3(c, d, b)) < 0;
}

const double inf = 4e18;

struct line{
    ll a, b;
    line(ll a = 0, ll b = 0) : a(a), b(b) {}
    double eval(double x){ return a * x + b; }
    bool operator < (const line& d){ return a < d.a; }
};

struct ConvexHullTrick{
    vector<line> v;
    ConvexHullTrick() : v() {}

    double inter(const line& d1, const line& d2){
        return 1.0 * (d2.b - d1.b) / (d1.a - d2.a);
    }

    void insert(ll a, ll b){
        line d(a, b);
        if(!v.empty() && v.back().a == a){
            if(v.back().b <= b) return;
            v.pop_back();
        }

        while(sz(v) > 1 && inter(v[sz(v) - 2], v.back()) >= inter(v.back(), d)){
            v.pop_back();
        } v.pb(d);
    }

    double query(double x){
        int l = 0, r = sz(v) - 1;
        while(l < r){
            int mid = l + r >> 1;
            if(v[mid].eval(x) >= v[mid + 1].eval(x)) l = mid + 1;
            else r = mid;
        }
        return v[l].eval(x);
    }
};

tuple<ll, ll, ll> line_equation_form(const point& P, const point& Q){
    ll a = Q.y - P.y;
    ll b = P.x - Q.x;
    ll c = -cross(P, Q);
    if(b < 0) a = -a, b = -b, c = -c;
    return mt(a, b, c);
}

void testcase(int num_testcase){
    int N;
    cin >> N;
    vector<point> pts(N);
    FOR(i, 0, N) cin >> pts[i];

    int M;
    cin >> M;
    vector<point> polygon(N);
    FOR(i, 0, M) cin >> polygon[i];

    sort(rall(polygon));
    ConvexHullTrick min_hull, max_hull;
    FOR(i, 0, M) min_hull.insert(polygon[i].x, polygon[i].y);
    ROF(i, M, 0) max_hull.insert(-polygon[i].x, -polygon[i].y);
    ll max_x = polygon.front().x, min_x = polygon.back().x;

    auto check = [&](const point& P, const point& Q) -> bool{
        ll a, b, c; tie(a, b, c) = line_equation_form(P, Q);
//        cout << dbg(a) << dbg(b) << dbg(c) << '\n';
        if(b == 0){
            ll mn_eval = min(min_x * a, max_x * a) + c;
            ll mx_eval = max(min_x * a, max_x * a) + c;
            if(mn_eval == 0 || mx_eval == 0) return true;
            if(sign(mn_eval) == sign(mx_eval)) return true;
            return false;
        } else{
            double frac = 1.0 * a / b;
            ll mn_eval = (1.0 * min_hull.query(frac) * b) + c;
            ll mx_eval = (-1.0 * max_hull.query(frac) * b) + c;
            if(mn_eval == 0 || mx_eval == 0) return true;
            if(sign(mn_eval) == sign(mx_eval)) return true;
            return false;
        }
        return true;
    };

    vi vis(N);
    vi mark(N, 0);
    FOR(i, 1, N){
        if(check(pts[0], pts[i])){
            vis.pb(i);
            mark[i] = true;
        }
    }

    for(auto u : vis){
        FOR(i, 1, N) if(!mark[i] && check(pts[u], pts[i])){
            mark[i] = true;
        }
    }

    cout << sum_of(mark) << '\n';
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

    file("task");

    int T = 1;
//    cin >> T;
    FOR(i, 0, T) testcase(i);

    return 0;
}

Compilation message (stderr)

relay.cpp: In function 'int main()':
relay.cpp:23:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |                         freopen(task".inp", "r", stdin); \
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
relay.cpp:232:5: note: in expansion of macro 'file'
  232 |     file("task");
      |     ^~~~
relay.cpp:24:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |                         freopen(task".out", "w", stdout); }
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
relay.cpp:232:5: note: in expansion of macro 'file'
  232 |     file("task");
      |     ^~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 19
• Subtask 3: 0 / 20
• Subtask 4: 0 / 43