Submission #954943

#	Time	Username	Problem	Language	Result	Execution time	Memory
954943		hyakup	Triangles (CEOI18_tri)	C++17	20 / 100	1 ms	600 KiB

tri

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

// int get_n(){
//   cout << "N: " << endl;
//   int x; cin >> x; return x;
// }
//
// bool is_clockwise( int a, int b, int c ){
//   cout << a << " " << b << " "<< c << endl;
//   int x; cin >> x; return x;
// }
//
// void give_answer( int x ){ cout << "RESP: " << x << endl; }

void ordena( vector<int>& v, vector<int>& resp ){
  if( v.size() == 1 ) return;
  vector<int> l, r;
  l.push_back(v[0]); r.push_back(v[0]);
  for( int i = 2; i < v.size(); i++ ){
    if( is_clockwise( v[0], v[1], v[i] ) ) r.push_back(v[i]);
    else l.push_back(v[i]);
  }
  ordena( l, resp ); resp.push_back(v[1]); ordena( r, resp );
}

int main(){
  mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
  int n = get_n();
  vector<int> v, resp;
  for( int i = 1; i <= n; i++ ) v.push_back(i);
  shuffle( v.begin(), v.end(), rng );
  ordena(v, resp);
  vector<int> hull; hull.push_back(v[0]);
  for( int cur : resp ){
    while( hull.size() >= 2 && !is_clockwise( hull[hull.size() - 2], hull.back(), cur ) ) hull.pop_back();
    hull.push_back(cur);
  }
  for( int i = 0; i < hull.size() - 1; i++ ){
    if( !is_clockwise(hull[i], hull[i + 1], hull.back()) ) continue;
    give_answer((int)hull.size() - i); break;
  }
}

Compilation message (stderr)

tri.cpp: In function 'void ordena(std::vector<int>&, std::vector<int>&)':
tri.cpp:22:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |   for( int i = 2; i < v.size(); i++ ){
      |                   ~~^~~~~~~~~~
tri.cpp: In function 'int main()':
tri.cpp:41:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |   for( int i = 0; i < hull.size() - 1; i++ ){
      |                   ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 20 / 20
• Subtask 5: 0 / 25