Submission #1052715

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052715		beaconmc	COVID tests (CEOI24_covid)	C++14	0 / 100	8 ms	344 KiB

Main

#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
#include <bits/stdc++.h>
 
typedef long long ll;
#define FOR(i,x,y) for(ll i=x; i<y; i++)
#define FORNEG(i,x,y) for(ll i=x; i>y; i--)

using namespace std;
/// You may use:

// The number of students
int N;

// The probability any given student is positive
double P;

// This function performs a test on a subset of samples.
// Its argument is a vector of Booleans of length N,
// where the i-th element is true if the i-th sample should be added to the mix.
// It returns true if (and only if) at least one of the samples in the mix is positive.
bool test_students(std::vector<bool> mask) {
    assert(mask.size() == (size_t)N);

    std::string mask_str(N, ' ');
    for (int i = 0; i < N; i++)
        mask_str[i] = mask[i] ? '1' : '0';

    printf("Q %s\n", mask_str.c_str());
    fflush(stdout);

    char answer;
    scanf(" %c", &answer);
    return answer == 'P';
}


vector<ll> dp(ll a, ll b, bool result){
    //cout << a << " " << b << " " << result << endl;
    if (result == 0) return {};
    if (a==b){
        if (result == 1) return {a};
        else return {};
    }
    ll mid = (a+b)/2;
    vector<ll> temp, temp2;
    vector<bool> test(N), test2(N);
    FOR(i,a,mid+1) test[i] = 1;
    FOR(i,mid+1,b+1) test2[i] = 1;

    if (rand()%2==0){
        ll result1 = test_students(test);
        temp = dp(a, mid, result1);
        ll result2 = -1;
        if (result1==0) result2 = 1;
        else result2 = test_students(test2);
        temp2 = dp(mid+1, b, result2);
    }else{
        ll result2 = test_students(test2);
        ll result1 = -1;
        temp2 = dp(mid+1, b, result2);
        
        if (result2==0) result1 = 1;
        else result1 = test_students(test);
        temp = dp(a, mid, result2);
        
    }

    
    vector<ll> ans;
    for (auto&i : temp) ans.push_back(i);
    for (auto&i : temp2) ans.push_back(i);
    return ans;
}

std::vector<bool> find_positive() {
    std::vector<bool> answer(N);
    vector<ll> stuff;
    vector<ll> temp;
    ll c;
    if (P>=0.068648) c = 4;
    else c = 1000;
    //cout << c << endl;
    FOR(i,0,(N-1)/c + 1){
        ll a = c*i;
        ll b = min(c*(i+1)-1, (ll)N-1);

        vector<bool> test(N);
        FOR(j,a,b+1) test[j] = 1;
        temp = dp(a, b, test_students(test));
        for (auto&k : temp) stuff.push_back(k);

    }
    
    FOR(i,0,N) answer[i] = 0;
    for (auto&i : stuff) answer[i] = 1;

    return answer;
}

int main() {
    int T;
    scanf("%d %lf %d", &N, &P, &T);

    // You may perform any extra initialization here.

    for (int i = 0; i < T; i++) {
        std::vector<bool> answer = find_positive();
        assert(answer.size() == (size_t)N);

        std::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);
        if (verdict == 'W')
            exit(0);
    }

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'std::vector<long long int> dp(ll, ll, bool)':
Main.cpp:62:12: warning: variable 'result1' set but not used [-Wunused-but-set-variable]
   62 |         ll result1 = -1;
      |            ^~~~~~~
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:35:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:105:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:121:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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