Submission #367656

#	Time	Username	Problem	Language	Result	Execution time	Memory
367656		rocks03	Counting Mushrooms (IOI20_mushrooms)	C++14	91.87 / 100	11 ms	512 KiB

mushrooms

//#pragma GCC target("avx2")
//#pragma GCC optimization("O3")
//#pragma GCC optimization("unroll-loops")
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ff first
#define ss second
#define pb push_back
#define SZ(x) ((int)(x).size())
#define all(x) x.begin(), x.end()
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define per(i, a, b) for(int i = (a); i >= (b); i--)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int use_machine(vector<int>);

int count_mushrooms(int N){
    vector<int> a = {0}, b;
    int ind = 1;
    vector<int> ask = {0, 1};
    int ans = use_machine(ask);
    ++ind;
    if(ans == 0) a.pb(1);
    else b.pb(1);
    if(N == 2) return SZ(a);
    if(SZ(a) < 2){
        ask = {0, 2};
        ans = use_machine(ask);
        if(ans == 1) b.pb(2);
        else a.pb(2);
        ++ind;
    }
    const int BOUND = 104;
    while(ind + 1 <= N - 1 && max(SZ(a), SZ(b)) < BOUND){
        if(SZ(a) >= SZ(b)){
            ask = {ind, a[0], ind + 1, a[1]};
            ans = use_machine(ask);
            if(ans == 0){
                a.pb(ind); a.pb(ind + 1);
            } else if(ans == 1){
                b.pb(ind); a.pb(ind + 1);
            } else if(ans == 2){
                a.pb(ind); b.pb(ind + 1);
            } else if(ans == 3){
                b.pb(ind); b.pb(ind + 1);
            }
            ind += 2;
        } else{
            ask = {ind, b[0], ind + 1, b[1]};
            ans = use_machine(ask);
            if(ans == 0){
                b.pb(ind); b.pb(ind + 1);
            } else if(ans == 1){
                a.pb(ind); b.pb(ind + 1);
            } else if(ans == 2){
                b.pb(ind); a.pb(ind + 1);
            } else if(ans == 3){
                a.pb(ind); a.pb(ind + 1);
            }
            ind += 2;
        }
    }
    if(ind == N) return SZ(a);
    if(ind + 1 == N){
        ask = {0, N - 1};
        ans = use_machine(ask);
        if(ans == 1) b.pb(N - 1);
        else a.pb(N - 1);
        ++ind;
        return SZ(a);
    }
    int answer = SZ(a);
    while(ind <= N - 1){
        if(SZ(a) >= SZ(b)){
            ask.clear();
            rep(i, 0, SZ(a)){
                if(ind > N - 1) break;
                ask.pb(a[i]);
                ask.pb(ind);
                ++ind;
            }
            ans = use_machine(ask);
            answer += SZ(ask) / 2 - (ans + 1) / 2;
            if(ans & 1){
                b.pb(ask.back());
            } else{
                a.pb(ask.back());
            }
        } else{
            ask.clear();
            rep(i, 0, SZ(b)){
                if(ind > N - 1) break;
                ask.pb(b[i]);
                ask.pb(ind);
                ++ind;
            }
            ans = use_machine(ask);
            answer += (ans + 1) / 2;
            if(ans & 1){
                a.pb(ask.back());
            } else{
                b.pb(ask.back());
            }
        }
    }
    return answer;
}

• Subtask 1: 91.8699 / 100