Submission #1222252

#	Time	Username	Problem	Language	Result	Execution time	Memory
1222252		jakeob77	COVID tests (CEOI24_covid)	C++20	Compilation error	0 ms	0 KiB

Main

#include <cassert>
#include <cstdio>
#include <string>
#include <vector>

/// 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';
}

/// You should implement:

// This function will be called once for each test instance.
// It should use test_students to determine which samples are positive.
// It must return a vector of Booleans of length N,
// where the i-th element is true if and only if the i-th sample is positive.
std::vector<bool> find_positive() {
    std::vector<bool> answer(N);
    vector<bool>find(N,false);
    for(int i=0;i<N;i++){
        find[i]=true;
        answer[i]=test_students(find);
        find[i]=false;
    }
    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<bool> find_positive()':
Main.cpp:41:5: error: 'vector' was not declared in this scope
   41 |     vector<bool>find(N,false);
      |     ^~~~~~
Main.cpp:41:5: note: suggested alternatives:
In file included from /usr/include/c++/11/vector:67,
                 from Main.cpp:4:
/usr/include/c++/11/bits/stl_vector.h:389:11: note:   'std::vector'
  389 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
In file included from Main.cpp:4:
/usr/include/c++/11/vector:86:13: note:   'std::pmr::vector'
   86 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
Main.cpp:41:12: error: expected primary-expression before 'bool'
   41 |     vector<bool>find(N,false);
      |            ^~~~
Main.cpp:43:9: error: 'find' was not declared in this scope; did you mean 'std::find'?
   43 |         find[i]=true;
      |         ^~~~
      |         std::find
In file included from /usr/include/c++/11/string:52,
                 from Main.cpp:3:
/usr/include/c++/11/bits/stl_algo.h:3876:5: note: 'std::find' declared here
 3876 |     find(_InputIterator __first, _InputIterator __last,
      |     ^~~~
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:29:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:52:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:68:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~