Submission #1073044

#	Time	Username	Problem	Language	Result	Execution time	Memory
1073044		Ignut	Counting Mushrooms (IOI20_mushrooms)	C++17	79.58 / 100	8 ms	604 KiB

mushrooms

// Ignut

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

mt19937 rnd(11223344);

int use_machine(vector<int> x);

int count_mushrooms(int n) {
    int res = 1;
    vector<int> A = {0}, B = {};
    vector<int> vec;
    for (int i = 1; i < n; i ++) vec.push_back(i);
    shuffle(vec.begin(), vec.end(), rnd);

    int firstA = 0, secondA = -1;
    // vector<int> vec;
    // for (int i = 1; i < n; i ++) vec.push_back(i);
    int SZ = 160;
    while (vec.size() > 1) {
        if (max(A.size(), B.size()) >= SZ) break;

        int u = vec.back(); vec.pop_back();
        int v = vec.back(); vec.pop_back();
        if (secondA != -1) {
            int val = use_machine({firstA, u, secondA, v});
            if (val == 0) {
                res += 2;
                A.push_back(u); A.push_back(v);
            }
            else if (val == 1) {
                res ++;
                A.push_back(u); B.push_back(v);
            }
            else if (val == 2) {
                res ++;
                A.push_back(v); B.push_back(u);
            }
            else {
                B.push_back(u), B.push_back(v);
            }
            continue; 
        }
        int val = use_machine({u, firstA, v});
        if (val == 0) {
            secondA = u;
            res += 2;
            A.push_back(u), A.push_back(v);
        }
        else if (val == 1) {
            res ++;
            val = use_machine({firstA, u});
            if (val == 0) {
                secondA = u;
                A.push_back(u), B.push_back(v);
            }
            else {
                secondA = v;
                A.push_back(v), B.push_back(u);
            }
        }
        else {
            B.push_back(u), B.push_back(v);
        }
    }

    if (vec.size() == 1) {
        int val = use_machine({firstA, vec.back()});
        if (val == 0) {
            res ++;
            A.push_back(vec.back());
        }
        else {
            B.push_back(vec.back());
        }
        vec.pop_back();
    }

    // ============================================================= //

    // int Q = 200;
    // for (int i = 0; i < Q; i ++) {
    //     if (vec.empty()) {
    //         return res;
    //     }
    //     int v = vec.back(); vec.pop_back();
    //     if (use_machine({0, v}) == 0) {
    //         res ++;
    //         A.push_back(v);
    //     }
    //     else {
    //         B.push_back(v);
    //     }
    //     if (max(A.size(), B.size()) >= 130)
    //         break;
    // }
    
    
    while (!vec.empty()) {
        int ind = 1;
        vector<int> ask = {(A.size() >= B.size() ? A[0] : B[0])};
        while (ind < max(A.size(), B.size()) && !vec.empty()) {
            int v = vec.back(); vec.pop_back();
            ask.push_back(v);
            ask.push_back(A.size() >= B.size() ? A[ind] : B[ind]);
            ind ++;
        }
        int val = use_machine(ask);
        int cnt = ind - 1;
        if (A.size() >= B.size())
            res += cnt - val / 2;
        else
            res += val / 2;
    }
    return res;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:25:37: warning: comparison of integer expressions of different signedness: 'const long unsigned int' and 'int' [-Wsign-compare]
   25 |         if (max(A.size(), B.size()) >= SZ) break;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
mushrooms.cpp:106:20: warning: comparison of integer expressions of different signedness: 'int' and 'const long unsigned int' [-Wsign-compare]
  106 |         while (ind < max(A.size(), B.size()) && !vec.empty()) {
      |                ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 79.5775 / 100