Submission #1078223

#	Time	Username	Problem	Language	Result	Execution time	Memory
1078223		oscar1f	COVID tests (CEOI24_covid)	C++17	100 / 100	2079 ms	11344 KiB

Main

#include<bits/stdc++.h>
#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
using namespace std;

/// You may use:

// The number of students
const int TAILLE_MAX=1000+5;
const double INFINI=1e9;
int N,nbTest;
vector<bool> rep;
vector<bool> attendu;
double puisP[TAILLE_MAX],puis1P[TAILLE_MAX];
double memo[TAILLE_MAX][TAILLE_MAX];
int suiv[TAILLE_MAX][TAILLE_MAX];

// 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(vector<bool> mask) {
    assert(mask.size() == (size_t)N);

    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';
}

/*bool test_students(vector<bool> mask) {
    nbTest++;
    bool ans=false;
    for (int i=0;i<N;i++) {
        if (mask[i] and attendu[i]) {
            ans=true;
        }
    }
    return ans;
}*/

bool askQuest(int deb,int fin) {
    vector<bool> quest(N);
    for (int i=deb;i<=fin;i++) {
        quest[i]=true;
    }
    return test_students(quest);
}

void dyna(int deb,int fin,int assure) {
    if (deb>fin) {
        return;
    }
    if (assure==1) {
        rep[deb]=true;
        dyna(deb+1,fin,0);
    }
    else {
        int taille=fin-deb+1;
        if (askQuest(deb,deb+suiv[assure][taille]-1)) {
            dyna(deb,fin,suiv[assure][taille]);
        }
        else if (assure==0) {
            dyna(deb+suiv[assure][taille],fin,0);
        }
        else {
            dyna(deb+suiv[assure][taille],fin,assure-suiv[assure][taille]);
        }
    }
}


/*void S9() {
    taille=8;
    for (int i=0;i<N;i+=taille) {
        bool trouve;
        vector<bool> quest(N);
        for (int j=i;j<i+taille;j++) {
            if (!rep[j]) {
                quest[j]=true;
            }
        }
        if (test_students(quest)) {
            trouve=
        }
        while (trouve) {
            trouve=dicho(i,min(i+taille-1,N-1),false);
        }
    }
}*/

/// 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.
vector<bool> find_positive() {
    rep.clear();
    rep.resize(N,false);
    dyna(0,N-1,0);
    return rep;
}

void init() {
    puisP[0]=1;
    puis1P[0]=1;
    for (int i=1;i<TAILLE_MAX;i++) {
        puisP[i]=puisP[i-1]*P;
        puis1P[i]=puis1P[i-1]*(1.0-P);
    }
    double esper,probGau;
    for (int taille=1;taille<TAILLE_MAX;taille++) {
        memo[1][taille]=memo[0][taille-1];
        for (int assure=2;assure<=taille;assure++) {
            memo[assure][taille]=INFINI;
            for (int i=1;i<assure;i++) {
                probGau=(1-puis1P[i])/(1-puis1P[assure]);
                esper=1.0+probGau*memo[i][taille]+(1-probGau)*memo[assure-i][taille-i];
                //cout<<esper<<endl;
                if (esper<memo[assure][taille]) {
                    memo[assure][taille]=esper;
                    suiv[assure][taille]=i;
                }
            }
        }
        memo[0][taille]=INFINI;
        for (int i=1;i<=taille;i++) {
            esper=1.0+(1.0-puis1P[i])*memo[i][taille]+puis1P[i]*memo[0][taille-i];
            //cout<<esper<<endl;
            if (esper<memo[0][taille]) {
                memo[0][taille]=esper;
                suiv[0][taille]=i;
            }
        }
    }
    /*for (int i=0;i<TAILLE_MAX;i++) {
        for (int j=0;j<TAILLE_MAX;j++) {
            cout<<memo[i][j]<<"  ";
        }
        cout<<endl;
    }
    for (int i=0;i<TAILLE_MAX;i++) {
        cout<<memo[0][i]<<" ";
    }*/
    //cout<<memo[0][1000]<<endl;
}

int main() {
    int T;
    scanf("%d %lf %d", &N, &P, &T);
    init();
    // 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;
}

/*int main() {
    int T;
    cin>>N>>P>>T;
    // You may perform any extra initialization here.
    init();
    char val;
    for (int i = 0; i < T; i++) {
        attendu.clear();
        for (int j=0;j<N;j++) {
            cin>>val;
            //cout<<val;
            attendu.push_back(val=='1');
        }
        std::vector<bool> answer = find_positive();
        for (int j=0;j<N;j++) {
            if (attendu[j]!=answer[j]) {
                cout<<"PROBLEME"<<" "<<i<<" "<<j<<endl;
                return 0;
            }
        }
    }
    cout<<nbTest/T<<endl;
    cout<<"OK"<<endl;
    return 0;
}*/

Compilation message (stderr)

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:162:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  162 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:178:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  178 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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