Submission #466351

#	Time	Username	Problem	Language	Result	Execution time	Memory
466351		ivan_tudor	Roads (CEOI20_roads)	C++14	0 / 100	2 ms	332 KiB

roads

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+ 5;
struct points{
  int x, y;
  int type;
  int id;
  bool operator <(points oth) const{
    if(y == oth.y)
      return id < oth.id;
    return y < oth.y;
  }
};
set<points> act;
pair<int, int> upper[N], lower[N];
bool cmp(points a, points b){
  if(a.x == b.x)
    return a.type < b.type;
  return a.x < b.x;
}
int v[N][4];
int main()
{
  freopen(".in","r",stdin);
  ios::sync_with_stdio(false);
  cin.tie(0),cout.tie(0);
  int n;
  cin>>n;
  vector<points> ev;
  for(int i =1 ; i <=n; i++){
    int x1, y1, x2, y2;
    cin>>x1>>y1>>x2>>y2;
    if(x1 >x2){
      swap(x1, x2);
      swap(y1, y2);
    }
    v[i][0] = x1;
    v[i][1] = y1;
    v[i][2] = x2;
    v[i][3] = y2;
    if(x1 == x2){
      ev.push_back({x1, y1, 2, i});
    }
    else{
      ev.push_back({x1, y1, 1, i});
      ev.push_back({x2, y2, 0, i});
    }
  }
  sort(ev.begin(), ev.end(), cmp);
  for(auto e : ev){
    if(e.type == 0){
      pair<int, int> last = {INT_MIN, INT_MIN};
      auto nxt = act.upper_bound({e});
      if(nxt != act.end()){
          last = upper[(*nxt).id];
          upper[(*nxt).id] = {e.x, e.y};
      }
      if(nxt != act.begin()){
        nxt = prev(nxt);
        if(lower[(*nxt).id].first > last.first)
          last =  lower[(*nxt).id];
        lower[(*nxt).id] = {e.x, e.y};
      }
      if(last.first != INT_MIN){
        cout<<last.first<<" "<<last.second<<" "<<e.x<<" "<<e.y<<"\n";
      }
      act.insert({e.x, e.y, 0, e.id});
      upper[e.id] = {e.x, e.y};
      lower[e.id] = {e.x, e.y};
    }
    else if(e.type == 1){
      auto itr = act.find({v[e.id][0], v[e.id][1], 0, e.id});
      assert(itr != act.end());
      auto nxt = next(itr);
      if(nxt != act.end()){
        upper[(*nxt).id] = {e.x, e.y};
      }
      if(itr != act.begin()){
        nxt = prev(itr);
        lower[(*nxt).id] = {e.x, e.y};
      }
      act.erase({v[e.id][0], v[e.id][1], 0, e.id});
    }
    else{
      int ys = v[e.id][1], yf = v[e.id][3];
      if(ys > yf)
        swap(ys, yf);
      pair<int, int> last = {INT_MIN, INT_MIN};
      int tp = 0;
      auto nxt = act.upper_bound({0, yf, 0, e.id});
      if(nxt != act.end()){
        last = upper[(*nxt).id];
        tp = 1;
        upper[(*nxt).id] = {e.x, yf};
      }
      if(nxt != act.begin()){
        nxt = prev(nxt);
        if(lower[(*nxt).id].first > last.first)
          last = lower[(*nxt).id], tp = 2;
        lower[(*nxt).id] = {e.x, ys};
      }
      if(tp == 1){
        cout<<last.first<<" "<<last.second<<" "<<e.x<<" "<<yf<<"\n";
      }
      else if(tp == 2){
        cout<<last.first<<" "<<last.second<<" "<<e.x<<" "<<ys<<"\n";
      }
    }
  }
  return 0;
}

Compilation message (stderr)

roads.cpp: In function 'int main()':
roads.cpp:24:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |   freopen(".in","r",stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 0 / 15
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 40