Submission #468149

#	Time	Username	Problem	Language	Result	Execution time	Memory
468149		ivan_tudor	Triangles (CEOI18_tri)	C++14	100 / 100	26 ms	2532 KiB

tri

#include<bits/stdc++.h>
#include"trilib.h"
using namespace std;
int root;
bool cmp(int x, int y){
  return is_clockwise(root, x, y);
}
vector<int> getstv(vector<int> v, int st, int en){
  root = st;
  sort(v.begin(), v.end(), cmp);
  vector<int> stv;
  stv.push_back(st);
  for(auto x: v){
    while(stv.size() > 1 && is_clockwise(stv.end()[-2], stv.end()[-1], x) == false)
      stv.pop_back();
    stv.push_back(x);
  }
  return stv;
}
mt19937 rng(time(0));
int main(){
  int n = get_n();
  int a = rng()%(n - 1) + 1;
  int b = rng()%(n - 1) + 1;
  while(b == a)
    b = rng()%(n - 1) + 1;
  vector<int> l, r;

  for(int i = 1; i<= n; i++){
    if(i == a)
      continue;
    if(i == b)
      continue;
    if(is_clockwise(a, b, i) == false)
      l.push_back(i);
    else
      r.push_back(i);
  }
 ///L ARE ORDINEA DE LA A LA B, R DE LA B LA A

  vector<int> stvl = getstv(l, a, b);
  vector<int> stvr = getstv(r, b, a);
  vector<int> stv = stvl;
  for(auto x: stvr){
    while(stv.size() > 1 && (is_clockwise(stv.end()[-2], stv.end()[-1], x) == false))
      stv.pop_back();
    stv.push_back(x);
  }
  for(auto x: stvl){
    while(stv.size() > 1 && (is_clockwise(stv.end()[-2], stv.end()[-1], x) == false))
      stv.pop_back();
    stv.push_back(x);
  }
  for(auto x: stvr){
    while(stv.size() > 1 && (is_clockwise(stv.end()[-2], stv.end()[-1], x) == false))
      stv.pop_back();
    stv.push_back(x);
  }
  vector<int> lap(n + 1, -1);
  int ans =INT_MAX;
  int pz = 0;
  for(auto x: stv){
    if(lap[x] != -1)
      ans = min(ans, pz - lap[x]);
    lap[x] = pz;
    pz++;
  }
  give_answer(ans);
}

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