Submission #54906

#	Time	Username	Problem	Language	Result	Execution time	Memory
54906		jklepec	Printed Circuit Board (CEOI12_circuit)	C++11	5 / 100	609 ms	33792 KiB

circuit

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

#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define REP(i, n) FOR(i, 0, n)
#define _ << " " <<
#define sz(x) ((int) x.size())

typedef long double lf;
typedef long long ll;
typedef pair<int, int> point;

const int MAXN = 1e5 + 5, inf = 1e9;
const lf eps = 1e-9;

int x[MAXN], y[MAXN];

lf K;

lf kk(int X, int Y) {
  return (lf) Y / X;
}

struct duz {
  lf k, l;
  lf lo, hi;
  bool usp;

  duz() {}
  duz(int i, int j) {
    lo = kk(x[i], y[i]);
    hi = kk(x[j], y[j]);

    if(lo > hi) swap(lo, hi);

    if(x[i] == x[j]) {
      usp = true;
      k = x[i];
    }
    else {
      k = (lf) (y[i] - y[j]) / (x[i] - x[j]);
      l = (lf) y[i] - k * x[i];
      usp = false;
    }
  }

  friend bool operator < (const duz &A, const duz &B);
} line[MAXN];

lf calc(duz A) {
  if(A.usp) return A.k;
  return A.l / (K - A.k);
}

bool operator < (const duz &A, const duz &B) {
  lf x1 = calc(A), x2 = calc(B);

  if(x1 == x2 && A.lo == K && B.lo == K) {
    K += eps;
    x1 = calc(A);
    x2 = calc(B);
    K -= eps;
  }
  else {
    K -= eps;
    x1 = calc(A);
    x2 = calc(B);
    K += eps;
  }

  return x1 < x2;
}

vector<pair<lf, point> > e;

void add(int i, int j) {
  line[i] = duz(i, j);

  lf k1 = kk(x[i], y[i]);
  lf k2 = kk(x[j], y[j]);

  if(k1 > k2) swap(k1, k2);

  e.push_back({k1 + eps, {0, i}});
  e.push_back({k2 - eps, {2, i}});
}

multiset<duz> s;
unordered_map<lf, int> m;

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

  int n; cin >> n;
  REP(i, n) {
    cin >> x[i] >> y[i];
    e.push_back({kk(x[i], y[i]), {1, i}});
    m[kk(x[i], y[i])] = max(m[kk(x[i], y[i])], inf - x[i]);
  }

  REP(i, n) {
    int j = (i + 1) % n;
    add(i, j);
  }

  sort(e.begin(), e.end());

  vector<int> sol(n, 0);
  for(auto p: e) {
    K = p.first;
    if(p.second.first == 0) {
      s.insert(line[p.second.second]);
    }
    if(p.second.first == 1) {
      if(sz(s) == 0) continue;
      duz X = *s.begin();
      if(calc(X) < x[p.second.second]) {
        sol[p.second.second] = true;
      }
    }
    if(p.second.first == 2) {
      s.erase(s.lower_bound(line[p.second.second]));
    }
  }

  vector<int> ans;
  REP(i, n) {
    if(!sol[i] && m[kk(x[i], y[i])] == inf - x[i]) ans.push_back(i);
  }

  cout << sz(ans) << endl;
  for(auto xx: ans) {
    cout << xx + 1 << " ";
  }
}

• Subtask 1: 5 / 100