제출 #1267792

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1267792		3lektra	COVID tests (CEOI24_covid)	C++20	68.32 / 100	776 ms	408 KiB

Main

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

bool setq(int b, int e){
    vector<bool> test(N,0);
    e = min(N-1, e);
    for(int i = b; i <= e; ++i) test[i] = 1;
    return test_students(test);
}

int binary_search(int l, int h){
    int mid = l +(h-l)/2;
    //cout << "In the binary search\n";
    while(l < h){
        //if(l == h) return h;
        //cout << mid << '\n';
        if(setq(l, mid)){
            h = mid;
            //cout << "p \t";
        }
        else{
            //if(h-l <= 3) return h; 
            l = mid+1;
            //if(l == h-1) return h;
            //cout << "n \t";
        }

        //cout << "wot " <<  l << ' ' << h << '\n';
        mid = l + (h-l)/2;
    }
    
    return mid;
}

vector<bool> case1() {
    vector<bool> answer(N, 0);
    vector<bool> test(N, 0);
    test[0] = 1;
    if(test_students(test)) answer[0] = true;
    for(int i = 1; i < N; ++i){
        test[i-1] = 0;
        test[i] = 1;
        if(test_students(test)) answer[i] = true;
    }
}


vector<bool> find_positive() {
    vector<bool> answer(N, 0);

    if(P == 0) return answer;
    if(P > 0.2) vector<bool> case1();


    int sz = 0.25/P;
    sz = min(sz, N);
    //cout << sz << '\n';

    int pos = 0;

    while(pos < N){
        //cout << pos << ' ' << N << '\n';
        if(setq(pos, pos+sz)){
            pos = binary_search(pos, pos+sz);
            //cout << pos << '\n';
            answer[pos] = 1;
            pos++;
            if(pos + sz >= N) sz = N-pos-1;
            //cout << "New cycle\n";
        }
        else pos = pos+sz+1;
    }
    /*
    if(pos != N && setq(pos, N-1)){
        if(pos + 1 == N){
            answer[pos] = 1;
        }
        else{
            pos = binary_search(pos, N-1);
            answer[pos] = 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;
}

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In function 'std::vector<bool> case1()':
Main.cpp:83:1: warning: no return statement in function returning non-void [-Wreturn-type]
   83 | }
      | ^
Main.cpp: In function 'std::vector<bool> find_positive()':
Main.cpp:90:35: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   90 |     if(P > 0.2) vector<bool> case1();
      |                                   ^~
Main.cpp:90:35: note: remove parentheses to default-initialize a variable
   90 |     if(P > 0.2) vector<bool> case1();
      |                                   ^~
      |                                   --
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:31:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:128:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:144:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  144 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 58.32 / 90