Submission #54972

#	Time	Username	Problem	Language	Result	Execution time	Memory
54972		dfistric	Printed Circuit Board (CEOI12_circuit)	C++14	60 / 100	143 ms	3520 KiB

circuit

#include <bits/stdc++.h>

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n)
#define point pair <int, int>
#define X first
#define Y second
#define ll long long

using namespace std;

const int MAXN = 100010;

struct line {
  point A, B;
};

line lines[MAXN];
point ray;
multiset <line> s;
vector <point> ve;
vector <int> out;
int arr[MAXN];
int n;

ll ccw(point a, point b, point c) {
  ll out = ((ll) a.X * (b.Y - c.Y)) +
           ((ll) b.X * (c.Y - a.Y)) +
           ((ll) c.X * (a.Y - b.Y));
  return out;
}

ll ccw0(point a, point b) {
  return ccw({0, 0}, a, b);
}

ll dist(point a) {
  return (a.X * a.X) + (a.Y * a.Y);
}

bool operator==(line x, line y) {
  return x.A == y.A && x.B == y.B;
}

bool operator< (line x, line y) {
  if (x == y) return 0;
  if (ccw0(x.A, x.B) < 0) swap(x.A, x.B);
  if (ccw0(y.A, y.B) < 0) swap(y.A, y.B);

  ll P = ccw(x.B, x.A, y.A) + ccw(x.B, y.A, y.B);

  if (P == 0) {
    if (x.A.Y == y.A.Y) return x.A.X < y.A.X;
    return x.A.Y < y.A.Y;
  }

  return P > 0;
}

bool cmp(int a, int b) {
  if (ccw0(ve[a], ve[b]) == 0) {
    return ve[a] < ve[b];
  }
  return ccw0(ve[a], ve[b]) > 0;
}

int main() {
  ios_base::sync_with_stdio(false);

  cin >> n;
  REP(i, n) {
    int a, b;
    cin >> a >> b;
    ve.push_back({a, b});
    arr[i] = i;
  }

  sort(arr, arr + n, cmp);
  //REP(i, n) cout << arr[i] + 1 << " "; cout << endl;

  REP(ind, n) {
    int i = arr[ind];
    point x = ve[i];
    ray = x;

    for (int t : {-1, 1}) {
      int j = (i + t + n) % n;
      point y = ve[j];
      
      if (cmp(i, j)) {
        line tr = {x, y};
        s.insert(tr);
      }
    }
    
    line tr = *s.begin();
    if (ccw(tr.A, tr.B, x) == 0) out.push_back(i);

    for (int t : {-1, 1}) {
      int j = (i + t + n) % n;
      point y = ve[j];

      if (!cmp(i, j)) {
        line tr = {y, x};
        s.erase(s.find(tr));
      }
    }
  }

  sort(out.begin(), out.end());
  cout << out.size() << "\n";
  for (int x : out) cout << x + 1 << " ";
  cout << "\n";

  return 0;
}

• Subtask 1: 60 / 100