Submission #1197671

#	Time	Username	Problem	Language	Result	Execution time	Memory
1197671		Zbyszek99	COVID tests (CEOI24_covid)	C++20	79.39 / 100	572 ms	468 KiB

Main

#include <bits/stdc++.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;

int n;
double P;

bool test_students(vi mask) 
{
    string mask_str(n, '0');
    forall(it,mask) mask_str[it] = '1';
    printf("Q %s\n", mask_str.c_str());
    fflush(stdout);
    char answer;
    scanf(" %c", &answer);
    return answer == 'P';
}

vector<bool> find_positive() 
{
    vector<bool> answer(n);
    int left = n*P;
    int cur_p = 0;
    int block = max(1,min(n-cur_p,(n-cur_p)/max(1,left)));
    vi elms;
    vi z;
    rep(i,n) z.pb(i);
    rep(i,n)
    {
        int ind = los(0,siz(z)-1);
        elms.pb(z[ind]);
        swap(z[ind],z[siz(z)-1]);
        z.pop_back();
    }
    while(cur_p < n)
    {
        block = min(block,n-cur_p);
        vi b = {};
        rep2(i,cur_p,cur_p+block-1) b.pb(elms[i]);
        bool is = test_students(b);
        if(!is)
        {
            cur_p += block;
            continue;
        }
        int l = cur_p;
        int r = cur_p+block-1;
        int ans = cur_p;
        while(l <= r)
        {
            int mid = (l+r)/2;
            if(mid == cur_p+block-1)
            {
                ans = mid;
                break;
            }
            b = {};
            rep2(i,cur_p,mid) b.pb(elms[i]);
            if(test_students(b))
            {
                ans = mid;
                r = mid-1;
            }
            else
            {
                l = mid+1;
            }
        }
        left--;
        answer[elms[ans]] = 1;
        cur_p = ans+1;
    }
    return answer;
}

int main() 
{
    random_start();
    int t;
    cin >> n >> P >> t;
    for (int i = 0; i < t; i++) 
    {
        vector<bool> answer = find_positive();
        string answer_str(n, ' ');
        for (int j = 0; j < n; j++)
        {
            answer_str[j] = answer[j] ? '1' : '0';
        }
        printf("A %s\n", answer_str.c_str());
        fflush(stdout);
        char verdict;
        scanf(" %c", &verdict);
    }
}

Compilation message (stderr)

Main.cpp: In function 'bool test_students(std::vector<int>)':
Main.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:117:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  117 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 69.39 / 90