Submission #955811

#	Time	Username	Problem	Language	Result	Execution time	Memory
955811		chrisvilches	Dragon 2 (JOI17_dragon2)	C++14	15 / 100	4029 ms	2512 KiB

dragon2

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

// TODO: New index category: point inside polygon (log N), and polygon tangent.

ll Bx, By;

struct Point {
  ll x, y;
  Point operator-(const Point p) const { return {x - p.x, y - p.y}; }
  Point operator+(const Point p) const { return {x + p.x, y + p.y}; }
  ll cross(const Point p) const { return x * p.y - y * p.x; }
  bool operator<(const Point p) const { return to_upper().cross(p.to_upper()) > 0; }
  Point to_upper() const { return above() ? *this : negate(); }
  bool above() const {
    const Point B{Bx, By};
    return B.cross(*this) > 0;
  }
  ll operator*(const Point p) const { return x * p.x + y * p.y; }
  bool deg0(const Point p) const { return cross(p) == 0 && *this * p >= 0; }
  bool deg180(const Point p) const { return cross(p) == 0 && *this * p < 0; }
  Point negate() const { return {-x, -y}; }
};
ostream& operator<<(ostream& os, const Point& p) {
  return os << "(" << p.x << ", " << p.y << ")";
}

short orientation(const Point o, const Point a, const Point b) {
  const ll cross = (a - o).cross(b - o);
  assert(cross != 0);
  return (cross > 0) - (cross < 0);
}

int handle_query(const vector<Point>& points1, const vector<Point>& points2,
                 const Point B) {
  set<Point> active;

  for (const auto q : points2) {
    if (!q.above()) {
      active.emplace(q);
    }
  }

  int total = 0;

  int j = 0;
  for (const Point p : points1) {
    while (j < (int)points2.size()) {
      const Point q = points2[j];
      if (q.to_upper().cross(p.to_upper()) < 0) {
        break;
      }
      if (q.above()) {
        assert(!active.count(q));
        active.emplace(q);
        assert(active.count(q));
      } else {
        assert(active.count(q));
        active.erase(q);
        assert(!active.count(q));
      }
      j++;
    }

    // TODO: (Brute force)
    for (const Point q : points2) {
      if (!active.count(q)) continue;
      if (p.above()) {
        if (orientation(B, p, q) > 0) total++;
      } else {
        if (orientation(p, B, q) > 0) total++;
      }
    }
  }

  return total;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int N, M, Q;

  while (cin >> N >> M) {
    vector<Point> points;
    unordered_map<int, vector<Point>> tribe_points;
    for (int i = 0; i < N; i++) {
      Point p;
      int tribe;
      cin >> p.x >> p.y >> tribe;
      tribe_points[tribe].push_back(p);
    }

    Point A;
    cin >> A.x >> A.y;
    cin >> Bx >> By;
    cin >> Q;
    Bx -= A.x;
    By -= A.y;
    const Point B{Bx, By};

    for (auto& [_, points] : tribe_points) {
      for (auto& p : points) {
        p = p - A;
      }

      sort(points.begin(), points.end());
    }

    while (Q--) {
      int i, j;
      cin >> i >> j;
      cout << handle_query(tribe_points[i], tribe_points[j], B) << '\n';
    }
  }
}

Compilation message (stderr)

dragon2.cpp: In function 'int main()':
dragon2.cpp:103:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  103 |     for (auto& [_, points] : tribe_points) {
      |                ^

• Subtask 1: 15 / 15
• Subtask 2: 0 / 45
• Subtask 3: 0 / 40