oj.uz

Submission #1119882

# Submission time Handle Problem Language Result Execution time Memory
1119882 2024-11-27T14:33:15 Z Tenis0206 COVID tests (CEOI24_covid) C++11
0 / 100
 4937 ms 504 KB 
#include <bits/stdc++.h>

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';
}

/// 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> answer;

bool my_test_students(int st, int dr)
{
    vector<bool> mask(N);
    for(int i=st; i<=dr; i++)
    {
        mask[i] = true;
    }
    return test_students(mask);
}

void divide(int st, int dr)
{
    if(st == dr)
    {
        answer[st] = true;
        return;
    }
    int mij = (st + dr) >> 1;
    bool ok_st = my_test_students(st, mij);
    bool ok_dr = my_test_students(mij + 1, dr);
    if(ok_st)
    {
        divide(st, mij);
    }
    if(ok_dr)
    {
        divide(mij + 1, dr);
    }
}

void find_positive()
{

    if(P < 2)
    {
        int poz = 0;
        while(poz < N)
        {
            int st = poz;
            int dr = min(N - 1, (int)(poz + 10 * (1 / P)));
            int rez = -1;
            while(st <= dr)
            {
                int mij = (st + dr) >> 1;
                bool ok = my_test_students(poz, mij);
                if(ok)
                {
                    rez = mij;
                    dr = mij - 1;
                }
                else
                {
                    st = mij + 1;
                }
            }
            if(rez == -1)
            {
                st = poz;
                dr = N - 1;
                rez = -1;
                while(st <= dr)
                {
                    int mij = (st + dr) >> 1;
                    bool ok = my_test_students(poz, mij);
                    if(ok)
                    {
                        rez = mij;
                        dr = mij - 1;
                    }
                    else
                    {
                        st = mij + 1;
                    }
                }
                if(rez == -1)
                {
                    break;
                }
            }
            answer[rez] = true;
            poz = rez + 1;
        }
    }
    else
    {
        vector<bool> mask(N);
        for(int i=0; i<N; i++)
        {
            mask[i] = false;
        }
        for(int i=0; i<N; i++)
        {
            mask[i] = true;
            bool ok = test_students(mask);
            answer[i] = ok;
            mask[i] = false;
        }
    }
}

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++)
    {
        answer.resize(N);
        for(int j=0; j<N; j++)
        {
            answer[j] = false;
        }
        find_positive();

        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

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:145:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  145 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:166:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  166 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 336 KB Output is correct

Subtask #1
0.0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 43 ms 348 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #2
0.0 / 90.0

# Verdict Execution time Memory Grader output
1 Correct 162 ms 504 KB Output is correct (P=0.001, F=15.1, Q=27.3) -> 21.27 points
2 Correct 330 ms 336 KB Output is correct (P=0.005256, F=51.1, Q=61.6) -> 49.40 points
3 Correct 655 ms 336 KB Output is correct (P=0.011546, F=94.9, Q=114.0) -> 49.86 points
4 Correct 1418 ms 336 KB Output is correct (P=0.028545, F=191.5, Q=240.5) -> 44.48 points
5 Correct 1712 ms 336 KB Output is correct (P=0.039856, F=246.3, Q=317.8) -> 41.64 points
6 Correct 2796 ms 336 KB Output is correct (P=0.068648, F=366.2, Q=491.6) -> 37.98 points
7 Correct 3855 ms 336 KB Output is correct (P=0.104571, F=490.3, Q=690.2) -> 34.21 points
8 Execution timed out 4937 ms 336 KB Time limit exceeded (wall clock)
9 Halted 0 ms 0 KB -