Submission #121220

#	Time	Username	Problem	Language	Result	Execution time	Memory
121220		BThero	Triangles (CEOI18_tri)	C++17	0 / 100	2 ms	384 KiB

tri

// Why am I so dumb? :c
// chrono::system_clock::now().time_since_epoch().count()
 
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
 
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include"trilib.h"
 
#define pb push_back
#define mp make_pair
 
#define all(x) (x).begin(), (x).end()
 
#define fi first
#define se second
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;   
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
const int MAXN = (int)4e4 + 5;
 
int idx[MAXN];
 
void solve() {
    int n = get_n();
 
    for (int i = 1; i < n; ++i) {
        idx[i] = i;    
    }
 
    for (int i = 1; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            if (is_clockwise(n, idx[j], idx[i]) == 0) {
                swap(idx[i], idx[j]);
            }        
        }
    }
 
    vector<int> V;
    V.pb(n);
    V.pb(idx[n - 1]);
 
    for (int i = n - 2; i > 0; --i) {
        while (V.size() >= 2 && !is_clockwise(V[V.size() - 2], V.back(), idx[i])) {
            V.pop_back();
        }
 
        V.pb(idx[i]);
    }

    while (V.size() > 3) {
        if (!is_clockwise(V.back(), V.front(), V[1])) {
            V.erase(V.begin());
        }
        else if (!is_clockwise(V[V.size() - 2], V.back(), V.front())) {
            V.pop_back();
        }
        else {
            break;
        }
    }          
 
    give_answer(V.size());
}
 
int main() {
    int tt = 1;
 
    while (tt--) {
        solve();
    }
 
    return 0;
}

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