Submission #1044541

#	Time	Username	Problem	Language	Result	Execution time	Memory
1044541		Tsovak	COVID tests (CEOI24_covid)	C++17	30.89 / 100	1739 ms	596 KiB

Main

// -------------------- Includes -------------------- //
#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <stdio.h>
#include <cstdlib>
#include <stdlib.h>
#include <array>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <math.h>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <tuple>
#include <utility>
#include <cassert>
#include <assert.h>
#include <climits>
#include <limits.h>
#include <ctime>
#include <time.h>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;

// -------------------- Typedefs -------------------- //

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;

// -------------------- Defines -------------------- //

#define pr pair
#define mpr make_pair
#define ff first
#define ss second

#define mset multiset
#define mmap multimap
#define uset unordered_set
#define umap unordered_map
#define umset unordered_multiset
#define ummap unordered_multimap
#define pqueue priority_queue

#define sz(x) (int((x).size()))
#define len(x) (int((x).length()))
#define all(x) (x).begin(), (x).end()
#define clr(x) (x).clear()

#define ft front
#define bk back
#define pf push_front
#define pb push_back
#define popf pop_front
#define popb pop_back

#define lb lower_bound
#define ub upper_bound
#define bs binary_search

// -------------------- Constants -------------------- //

const int MAX = int(1e9 + 5);
const ll MAXL = ll(1e18 + 5);
const ll MOD = ll(1e9 + 7);
const ll MOD2 = ll(998244353);

// -------------------- Solution -------------------- //

/// 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.
vector<bool> ans;

bool qry(int l, int r)
{
	vector<bool> msk(N, 0);
	for (int i = l; i <= r; i++) msk[i - 1] = 1;

	return test_students(msk);
}

void calc(int tl, int tr)
{
	if (tl == tr) {
		if (qry(tl, tr)) ans.pb(1);
		else ans.pb(0);

		return;
	}

	int m = (tl + tr) / 2;


	if (qry(tl, m)) {
		if (tl == m) ans.pb(1);
		else calc(tl, m);
	}
	else for (int i = tl; i <= m; i++) ans.pb(0);

	if (qry(m + 1, tr)) {
		if (m + 1 == tr) ans.pb(1);
		else calc(m + 1, tr);
	}
	else for (int i = m + 1; i <= tr; i++) ans.pb(0);

	return;
}

vector<bool> find_positive()
{
	int i, j;

	clr(ans);

	int h = int(db(N) * P);

	//calc(1, N);

	int len = min(N, (N * 3) / (h * 2));

	for (i = 1; i <= N; i += len) calc(i, min(N, i + len - 1));

	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++) {
		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 'std::vector<bool> find_positive()':
Main.cpp:161:9: warning: unused variable 'j' [-Wunused-variable]
  161 |  int i, j;
      |         ^
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:112:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |  scanf(" %c", &answer);
      |  ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:179:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  179 |  scanf("%d %lf %d", &N, &P, &T);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:195:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  195 |   scanf(" %c", &verdict);
      |   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 30.889999997999997 / 90