Submission #826142

#	Time	Username	Problem	Language	Result	Execution time	Memory
826142		Sam_a17	Triangles (CEOI18_tri)	C++17	75 / 100	17 ms	1944 KiB

tri

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
// #include "B.cpp"
#include "trilib.h"
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt(x) __builtin_popcount(x)
 
#define pb push_back
#define popf pop_front
#define popb pop_back
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
 
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
 
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if (str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

int get_n();
int is_clockwise(int a, int b, int c);
void give_answer(int s);

int m, ind = -1;

bool cmp(int a, int b) {
  if(is_clockwise(ind, a, b)) {
    return true;
  } else {
    return false;
  }
}

void solve_() {
  m = get_n();

  vector<int> ral;
  for(int i = 1; i <= m; i++) {
    ral.push_back(i);
  }
  random_shuffle(all(ral));
  vector<int> l, r;

  int one = ral[0], two = ral[1];

  for(int i = 1; i <= m; i++) {
    if(i == one || i == two) continue;
    if(is_clockwise(one, two, i)) {
      r.push_back(i);
    } else {
      l.push_back(i);
    }
  }
  ind = ral[0];
  sort(all(r), cmp);
  r.push_back(one);

  sort(all(l), cmp);
  l.push_back(two);


  if(sz(r) < sz(l)) {
    vector<bool> have_r(m + 1);
    for(auto i: r) {
      have_r[i] = true;
    }

    vector<int> mer = r;
    for(auto i: l) mer.push_back(i);

    vector<int> st;
    for(int i = 0; i < sz(mer); i++) {
      while(sz(st) >= 2 && !is_clockwise(st[sz(st) - 2], st.back(), mer[i])) {
        st.pop_back();
      }
      st.push_back(mer[i]);
    }

    int sub = 0;
    vector<int> bit;
    for(auto i: st) {
      if(have_r[i]) {
        bit.push_back(i);
        sub++;
      }
    }

    for(int i = 0; i < sz(bit); i++) {
      while(sz(st) >= 2 && !is_clockwise(st[sz(st) - 2], st.back(), bit[i])) {
        st.pop_back();
      }
      st.push_back(bit[i]);
    }
    int nw = sz(st);
    cout << nw - sub << '\n';
  } else {
    vector<bool> have_r(m + 1);
    for(auto i: l) {
      have_r[i] = true;
    }

    vector<int> mer = l;
    for(auto i: r) mer.push_back(i);

    vector<int> st;
    for(int i = 0; i < sz(mer); i++) {
      while(sz(st) >= 2 && !is_clockwise(st[sz(st) - 2], st.back(), mer[i])) {
        st.pop_back();
      }
      st.push_back(mer[i]);
    }

    int sub = 0;
    vector<int> bit;
    for(auto i: st) {
      if(have_r[i]) {
        bit.push_back(i);
        sub++;
      }
    }

    for(int i = 0; i < sz(bit); i++) {
      while(sz(st) >= 2 && !is_clockwise(st[sz(st) - 2], st.back(), bit[i])) {
        st.pop_back();
      }
      st.push_back(bit[i]);
    }
    int nw = sz(st);
    cout << nw - sub << '\n';
  }
}
 
int main() {
  fastIO();
 
  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };
 
  int test_cases = 1;
  // cin >> test_cases;
  solve(test_cases);
 
  return 0;
} 

Compilation message (stderr)

tri.cpp: In function 'void setIO(std::string)':
tri.cpp:66:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tri.cpp:67:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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