Submission #1193147

#TimeUsernameProblemLanguageResultExecution timeMemory
1193147UnforgettableplCOVID tests (CEOI24_covid)C++20
98.70 / 100
762 ms408 KiB
#include <bits/stdc++.h> using namespace std; /// You may use: // The number of students int N; int jump; // 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); 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. vector<bool> find_positive() { vector<bool> answer(N); vector<int> idxes(N); iota(idxes.begin(),idxes.end(),0ll); shuffle(idxes.begin(),idxes.end(),mt19937(6655215)); auto query = [&](int a,int b){ vector<bool> q(N); for(int i=a;i<=b;i++)q[idxes[i]]=true; return test_students(q); }; auto getBeforeNext = [&](int x){ if(x==N-1)return N-1; while(true){ int tryX = min(x+jump,N-1); if(query(x+1,tryX)){ int L = x+1; int R = tryX; while(L<R){ int siz = R-L+1; long double invP = 1.0-P; int pick = llroundl((logl(1+powl(invP,siz))-logl(2))/logl(invP)); pick+=L-1; pick = min(max(pick,L),R-1); if(query(L,pick)){ R = pick; } else { L = pick+1; } } return L-1; } else { x=tryX; if(x==N-1)return N-1; } } }; int x = getBeforeNext(-1); while(x!=N-1){ answer[idxes[++x]]=true; x = getBeforeNext(x); } return answer; } int main() { int T; scanf("%d %lf %d", &N, &P, &T); // You may perform any extra initialization here. jump = max(1ll,llroundl(-1.0/log2l(1-P))); 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 (stderr)

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:27:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:83:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:98:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~
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