Submission #1313969

#	Time	Username	Problem	Language	Result	Execution time	Memory
1313969		Zbyszek99	Triangles (CEOI18_tri)	C++17	100 / 100	432 ms	53396 KiB

tri

#include <bits/stdc++.h>
#include "trilib.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

map<ll,bool> ans_map;

bool ask(int a, int b, int c)
{
    ll x = a+1e5*(ll)b+1e10*(ll)c;
    if(ans_map.find(x) != ans_map.end()) return ans_map[x];
    ans_map[x] = is_clockwise(a,b,c);
    return ans_map[x];
}

bool comp(int a, int b)
{
    return !ask(1,a,b);
}

vi get_hull(vi p, int a, int b)
{
    sort(all(p),comp);
    vi ans = {a,b};
    forall(it,p)
    {
        while(true)
        {
            int p1 = ans[siz(ans)-2];
            int p2 = ans[siz(ans)-1];
            if(!ask(p1,p2,it)) break;
            else ans.pop_back();
        }
        ans.pb(it);
    }
    vi ans2;
    rep2(i,2,siz(ans)-1) ans2.pb(ans[i]);
    return ans2;
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    int n = get_n();
    vi p1;
    vi p2;
    rep2(i,3,n)
    {
        if(!ask(1,2,i)) p1.pb(i);
        else p2.pb(i);
    }
    p1 = get_hull(p1,1,2);
    p2 = get_hull(p2,2,1);
    p1.pb(1);
    vi pom = {2};
    forall(it,p1) pom.pb(it);
    p1 = pom;
    if(siz(p2) == 0)
    {
        give_answer(siz(p1));
        return 0;
    }
    int p1_l = 0;
    int p1_r = siz(p1)-1;
    int p2_l = 0;
    int p2_r = siz(p2)-1;
    while(true)
    {
        bool c1 = ask(p2[p2_r],p1[p1_l],(p1_l != p1_r ? p1[p1_l+1] : p2[p2_r]));
        bool c2 = ask((p2_r != p2_l ? p2[p2_r-1] : p1[p1_r]),p2[p2_r],p1[p1_l]);
        if(!c1 && !c2) break;
        if(c1) p1_l++;
        else p2_r--;
    }
    while(true)
    {
        bool c1 = ask(p2[p2_l],p1[p1_r],(p1_l != p1_r ? p1[p1_r-1] : p2[p2_r]));
        bool c2 = ask((p2_l != p2_r ? p2[p2_l+1] : p1[p1_l]),p2[p2_l],p1[p1_r]);
        if(c1 && c2) break;
        if(!c1) p1_r--;
        else p2_l++;
    }
    give_answer(p1_r-p1_l+p2_r-p2_l+2);
}

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