Submission #468356

#	Time	Username	Problem	Language	Result	Execution time	Memory
468356		kessido	Counting Mushrooms (IOI20_mushrooms)	C++17	Compilation error	0 ms	0 KiB

mushrooms

#include <bits/stdc++.h>
using namespace std;

#define ll long long int
#define vll vector<ll>
#define vi vector<int>
#define pi pair<int, int>
#define pll pair<ll, ll>
#define all(x) (x).begin(), (x).end()
#define fori(i,n) for(int i = 0; i < int(n); ++i)

bool test_is_a(int i) {
    return use_machine(vi{0, i}) == 0;
}

int count_mushrooms(int n) {
    vi opts(n-1);
    fori(i, n-1) opts[i] = i + 1;
    random_shuffle(all(opts));

    auto pop1 = [&]() {
        int i = opts.back();
        opts.pop_back();
        return i;
    };
    auto pop2 = [&]() -> pi { return {pop1(), pop1()}; };

    vi as = {0};
    vi bs = {};

    auto add_to_list = [&](int idx, bool is_a) {
        if(is_a) as.push_back(idx);
        else     bs.push_back(idx);
    };

    auto biggest_list_size = [&]() { return max(as.size(), bs.size()); };
    auto get_bigger_list = [&]() -> pair<vi&, bool> {
        if(as.size() >= bs.size()) return {as, true};
        else                       return {bs, false}; 
    };

    while (biggest_list_size() < 2) {
        int i = pop1();
        add_to_list(i, test_is_a(i));
    }

    while (biggest_list_size() < 76) {
        auto [i1, i2] = pop2();
        const auto& [ls, use_a] = get_bigger_list();
        vi test = {i1, ls[0], i2, ls[1]};
        
        int res = use_machine(test);
        add_to_list(i1, ((res&1) == 1) ^ use_a);
        add_to_list(i2, ((res&2) == 2) ^ use_a);
    }

    int as_count = 0;
    int bs_count = 0;
    
    while (!opts.empty()) {
        const auto& [ls, use_a] = get_bigger_list();
        vi test;
        for(int i : ls) {
            if(opts.empty()) break;
            test.push_back(pop1());
            test.push_back(i);
        }
        int res = use_machine(test);
        add_to_list(test[0], (res&1) ^ use_a);
        int bc1 = res >> 1;
        int ac1 = test.size()/2 - 1 - bc1;
        if (!use_a) swap(ac1, bc1);
        as_count += ac1;
        bs_count += bc1;
    }
    as_count += as.size();
    bs_count += bs.size();
    
    return as_count;
}

Compilation message (stderr)

mushrooms.cpp: In function 'bool test_is_a(int)':
mushrooms.cpp:13:12: error: 'use_machine' was not declared in this scope
   13 |     return use_machine(vi{0, i}) == 0;
      |            ^~~~~~~~~~~
mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:52:19: error: 'use_machine' was not declared in this scope
   52 |         int res = use_machine(test);
      |                   ^~~~~~~~~~~
mushrooms.cpp:68:19: error: 'use_machine' was not declared in this scope
   68 |         int res = use_machine(test);
      |                   ^~~~~~~~~~~