Submission #1040862

# Submission time Handle Problem Language Result Execution time Memory
1040862 2024-08-01T10:58:15 Z elazarkoren COVID tests (CEOI24_covid) C++17
0 / 100
154 ms 3760 KB
#include <bits/stdc++.h>
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define chkmin(a, b) a = min(a, b)
#define chkmax(a, b) a = max(a, b)
using namespace std;
typedef long long ll;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef pair<ll, ll> pii;
typedef vector<pii> vii;
typedef vector<bool> vb;
/// 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.

map<vb, bool> mp;

bool test_students(std::vector<bool> mask) {
    if (mp.count(mask)) return mp[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 mp[mask] = (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.

mt19937 rng(time(0));

int mrand(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

int FindNext(int l, int r, vi &ind) {
    vb mask(n);
    for (int i = l; i < r; i++) mask[ind[i]] = 1;
    if (!test_students(mask)) return r;
    for (int i = l; i < r; i++) mask[ind[i]] = 0;
    int begin = l + 1, end = r;
    while (begin < end) {
        int mid = (begin + end) >> 1;
        for (int i = l; i < mid; i++) mask[ind[i]] = 1;
        if (test_students(mask)) end = mid;
        else begin = mid + 1;
        for (int i = l; i < mid; i++) mask[ind[i]] = 0;
    }
    return end - 1;
}

void Solve(int l, int r, vi &ind, vb &ans) {
    while (l < r) {
        int nx = FindNext(l, r, ind);
        ans[nx] = 1;
        l = nx + 1;
    }
}

int cnt = 0;

void Solve2(int l, int r, vb &ans) {
    if (l + 1 == r) {
        cnt++;
        ans[l] = 1;
        return;
    }
    if (mrand(0, 1)) {
        vb test(n);
        int mid = (l + r) >> 1;
        fill(test.begin() + l, test.begin() + mid, 1);
        bool b = test_students(test);
        fill(test.begin() + l, test.begin() + mid, 0);
        if (!b) {
            Solve2(mid, r, ans);
            return;
        }
        Solve2(l, mid, ans);
        if (cnt > 2 * n * P) return;
        fill(test.begin() + mid, test.begin() + r, 1);
        b = test_students(test);
        fill(test.begin() + mid, test.begin() + r, 0);
        if (b) Solve2(mid, r, ans);
    } else {
        vb test(n);
        int mid = (l + r) >> 1;
        fill(test.begin() + mid, test.begin() + r, 1);
        bool b = test_students(test);
        fill(test.begin() + mid, test.begin() + r, 0);
        if (!b) {
            Solve2(l, mid, ans);
            return;
        }
        Solve2(mid, r, ans);
        if (cnt > 2 * n * P) return;
        fill(test.begin() + l, test.begin() + mid, 1);
        b = test_students(test);
        fill(test.begin() + l, test.begin() + mid, 0);
        if (b) Solve2(l, mid, ans);
    }
}

vb find_positive() {
//    if (P > 0.16) {
//        vb ans(n);
//        vb mask(n);
//        for (int i = 0; i < n; i += 2) {
//            mask[i] = mask[i + 1] = 1;
//            bool b = test_students(mask);
//            mask[i] = mask[i + 1] = 0;
//            if (b) {
//                int j = i, k = i + 1;
//                if (mrand(0, 1)) swap(j, k);
//                mask[j] = 1;
//                ans[j] = test_students(mask);
//                mask[j] = 0, mask[k]=  1;
//                if (!ans[j]) ans[k] = 1;
//                else ans[k] = test_students(mask);
//                mask[k] = 0;
//            }
//        }
//        return ans;
//    }
//    if (P < 0.05) {
        vb ans(n);
        vi ind(n);
        iota(all(ind), 0);
        while (!ind.empty()) {
            vi nx;
            shuffle(all(ind), rng);
            int m = ind.size();
            int blocks = min<int>(m, ceil(m * P * 2));
            int len = (m + blocks - 1) / blocks;
            for (int i = 0; i < m; i += len) {
//            Solve(i, min(i + len, n), ans);
                int l = i, r = min(i + len, m);
                int j = FindNext(l, r, ind);
                if (j < r) ans[ind[j++]] = 1;
                for (int k = j; k < r; k++) nx.push_back(ind[k]);
            }
            swap(ind, nx);
        }
        return ans;
//    }


//    vb ans(n);
//    cnt = 0;
//    Solve2(0, n, ans);
//    return ans;

//    int block = 1000;
//    for (int i = 0; i < n; i += block) Solve(i, i + block, ans);

//    Solve(0, n, answer);
//    vb test(n);
//    for (int i = 0; i < n; i++) {
//        test[i] = 1;
//        answer[i] = test_students(test);
//        test[i] = 0;
//    }
//    return ans;
}

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++) {
        vb answer = find_positive();
        assert(answer.size() == (size_t)n);

        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:41:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:189:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  189 |     scanf("%d %lf %d", &n, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:205:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  205 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~
# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 344 KB translate:wrong
2 Halted 0 ms 0 KB -
# Verdict Execution time Memory Grader output
1 Correct 22 ms 776 KB Output is correct
2 Correct 20 ms 600 KB Output is correct
3 Correct 18 ms 848 KB Output is correct
4 Correct 18 ms 644 KB Output is correct
5 Correct 18 ms 528 KB Output is correct
6 Correct 18 ms 600 KB Output is correct
7 Correct 18 ms 600 KB Output is correct
8 Correct 17 ms 600 KB Output is correct
9 Correct 18 ms 600 KB Output is correct
10 Correct 11 ms 812 KB Output is correct
11 Correct 16 ms 644 KB Output is correct
12 Correct 18 ms 600 KB Output is correct
13 Correct 19 ms 848 KB Output is correct
14 Correct 18 ms 808 KB Output is correct
15 Correct 21 ms 844 KB Output is correct
16 Correct 18 ms 728 KB Output is correct
17 Runtime error 1 ms 344 KB Execution killed with signal 8
18 Halted 0 ms 0 KB -
# Verdict Execution time Memory Grader output
1 Correct 40 ms 1216 KB Output is correct (P=0.001, F=15.1, Q=10.9) -> 90.00 points
2 Incorrect 154 ms 3760 KB translate:wrong
3 Halted 0 ms 0 KB -