Submission #1206430

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206430		asli_bg	Triangles (CEOI18_tri)	C++20	100 / 100	15 ms	1988 KiB

tri

#include <bits/stdc++.h>
using namespace std;
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

//#define int long long

#include "trilib.h"
 
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<pll> vll;
 
typedef tree<pii,null_type,less<pii>,rb_tree_tag,
tree_order_statistics_node_update> oset;
 
#define fi first
#define se second
#define pb push_back
#define pf push_front
 
#define mid (l+r)/2
#define all(x) x.begin(),x.end()
#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)
 
#define cont(x) for(auto el:x) cout<<el<<' ';cout<<endl;
#define contp(x) for(auto el:x) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;
#define sp <<" "<<
 
#define DEBUG(x) cout<<(#x) sp x<<endl
#define carp(a,b) (((a%MOD)*(b%MOD))%MOD)
#define topla(a,b) (((a%MOD)+(b%MOD))%MOD)
 
const ll INF=1e18;
const int MAXN=1e5+5;
const int MAXNN=2e5+5;
const int MOD=1e9+7;

vi tut[2];

int piv;

bool mm(int a,int b){
    return is_clockwise(piv,a,b);
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int n=get_n();
    if(n==3) give_answer(3);
    else{
        FORE(i,3,n+1){
            if(is_clockwise(1,2,i)) tut[0].pb(i);
            else tut[1].pb(i);
        }

        piv=1;
        sort(all(tut[0]),mm);
        piv=2;
        sort(all(tut[1]),mm);
        tut[0].pb(1);
        tut[1].pb(2);

        for(auto el:tut[0]) tut[1].pb(el);
    
        vi vec;
        for(auto el:tut[1]){
            int sz=vec.size();
            while(vec.size()>=2 and !is_clockwise(vec[sz-2],vec[sz-1],el)){
                vec.pop_back();
                sz=vec.size();
            }
            vec.pb(el);
        }

        int cikar=vec.size();

        for(auto el:tut[1]){
            int sz=vec.size();
            while(vec.size()>=2 and !is_clockwise(vec[sz-2],vec[sz-1],el)){
                vec.pop_back();
                sz=vec.size();
            }
            vec.pb(el);
        }

        int ans=vec.size();
        ans-=cikar;

        give_answer(ans);
    }
}

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