oj.uz

Submission #1074649

# Submission time Handle Problem Language Result Execution time Memory
1074649 2024-08-25T11:41:41 Z GrindMachine COVID tests (CEOI24_covid) C++17
70.45 / 100
 2537 ms 1156 KB 
#include <bits/stdc++.h>
using namespace std;
 
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define conts continue
#define sz(a) (int)a.size()
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define ceil2(x,y) ((x+y-1)/(y))
 
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
 
template<typename T>
void amin(T &x, T y){
    x = min(x,y);
}
 
template<typename T>
void amax(T &x, T y){
    x = max(x,y);
}
 
template<typename A,typename B>
string to_string(pair<A,B> p);
 
string to_string(const string &s){
    return "'"+s+"'";
}
 
string to_string(const char* s){
    return to_string((string)s);
}
 
string to_string(bool b){
    return b?"true":"false";
}
 
template<typename A>
string to_string(A v){
    string res = "{";
    trav(x,v){
        res += to_string(x)+",";
    }
    if(res.back() == ',') res.pop_back();
    res += "}";
    return res;
}
 
template<typename A,typename B>
string to_string(pair<A,B> p){
    return "("+to_string(p.ff)+","+to_string(p.ss)+")";
}
 
#define debug(x) cout << "[" << #x << "]: "; cout << to_string(x) << endl

/*

refs:
edi

*/ 

const int MOD = 1e9 + 7;
const int NN = 1e3 + 5;
const int inf1 = 1e9 + 5;
const ll inf2 = (ll)1e18 + 5;

bool dbg = false;

/// 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) {
    if(dbg) return 'P';

    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';
}
 

std::vector<ld> dp(NN,1e9);
std::vector<ld> dp2(NN,1e9);
std::vector<int> par(NN,-1);
std::vector<int> par2(NN,-1);

void precalc(){
    int n = N;
    dp[0] = dp[1] = 0;
    dp2[0] = 0, dp2[1] = 1;
    par2[1] = 1;
    for(int i = 2; i <= n; ++i){
        ld tot_neg = powl((ld)1-P, i);
        for(int j = 1; j < i; j++){
            ld all_neg2 = powl((ld)1-P,i-j);
            ld all_neg = powl((ld)1-P,j) * (1 - all_neg2) / (1 - tot_neg);
            ld val = 1+all_neg*dp[i-j];
            val += (1-all_neg)*(dp[j]+dp2[i-j]);
            if(val < dp[i]){
                dp[i] = val;
                par[i] = j;                
            }
        }
        for(int j = 1; j <= i; j++){
            ld all_neg = powl((ld)1-P,j);
            ld val = 1+(1-all_neg)*dp[j]+dp2[i-j];
            if(val < dp2[i]){
                dp2[i] = val;
                par2[i] = j;                
            }
        }
        // std::cout << "at N = " << i << " got ev " << dp[i] << " and par is " << par[i] << '\n';
        // std::cout << "at N = " << i << " got ev " << dp2[i] << " and par is " << par2[i] << '\n';
    }
}

/// 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);
    // return answer;
    int n = N;
    vector<bool> ans(n);

    auto go = [&](int l, int r, int t, auto &&go) -> void{
        // t = 0: positive not guaranteed (use dp2)
        // t = 1: at least 1 positive (use dp)
        if(l > r) return;

        int len = r-l+1;

        if(t){
            if(len == 1){
                ans[l] = 1;
                return;
            }

            int j = par[len];
            vector<bool> mask(n);
            for(int k = l; k < l+j; ++k){
                mask[k] = 1;
            }

            if(!test_students(mask)){
                // no positive on left
                // at least 1 positive on right
                go(l+j,r,1,go);
            }
            else{
                // at least 1 positive on left
                // not guaranteed on right
                go(l,l+j-1,1,go);
                go(l+j,r,0,go);
            }
        }
        else{
            if(len == 1){
                vector<bool> mask(n);
                mask[l] = 1;
                ans[l] = test_students(mask);
                return;
            }

            int j = par2[len];
            vector<bool> mask(n);
            for(int k = l; k < l+j; ++k){
                mask[k] = 1;
            }

            if(!test_students(mask)){
                // no positive on left
                // not guaranteed on right
                go(l+j,r,0,go);
            }
            else{
                // positive on left
                // not guaranteed on right
                go(l,l+j-1,1,go);
                go(l+j,r,0,go);
            }
        }
    };

    go(0,n-1,0,go);
    return ans;
}
 
int main() {
    #ifdef LOCAL
        dbg = true;
    #endif

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

    // 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

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:107:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:228:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  228 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:245:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  245 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 741 ms 696 KB Output is correct
2 Correct 750 ms 696 KB Output is correct
3 Correct 723 ms 700 KB Output is correct
4 Correct 745 ms 700 KB Output is correct
5 Correct 732 ms 592 KB Output is correct
6 Correct 745 ms 696 KB Output is correct
7 Correct 757 ms 712 KB Output is correct
8 Correct 746 ms 576 KB Output is correct
9 Correct 743 ms 720 KB Output is correct
10 Correct 731 ms 344 KB Output is correct
11 Correct 745 ms 592 KB Output is correct
12 Correct 751 ms 592 KB Output is correct
13 Correct 711 ms 1156 KB Output is correct
14 Correct 748 ms 440 KB Output is correct
15 Correct 746 ms 592 KB Output is correct
16 Correct 60 ms 596 KB Output is correct
17 Correct 712 ms 444 KB Output is correct

Subtask #2
60.450000003 / 90.0

# Verdict Execution time Memory Grader output
1 Correct 730 ms 592 KB Output is correct (P=0.001, F=15.1, Q=13.2) -> 90.00 points
2 Correct 839 ms 344 KB Output is correct (P=0.005256, F=51.1, Q=55.9) -> 65.42 points
3 Correct 976 ms 444 KB Output is correct (P=0.011546, F=94.9, Q=106.5) -> 60.45 points
4 Correct 1237 ms 592 KB Output is correct (P=0.028545, F=191.5, Q=214.2) -> 61.05 points
5 Correct 1396 ms 444 KB Output is correct (P=0.039856, F=246.3, Q=273.3) -> 62.57 points
6 Correct 1602 ms 456 KB Output is correct (P=0.068648, F=366.2, Q=398.8) -> 66.37 points
7 Correct 2021 ms 488 KB Output is correct (P=0.104571, F=490.3, Q=523.0) -> 71.05 points
8 Correct 2384 ms 496 KB Output is correct (P=0.158765, F=639.1, Q=664.1) -> 77.82 points
9 Correct 2537 ms 344 KB Output is correct (P=0.2, F=731.4, Q=750.0) -> 81.69 points