Submission #390699

#	Time	Username	Problem	Language	Result	Execution time	Memory
390699		JimmyZJX	Combo (IOI18_combo)	C++14	100 / 100	45 ms	572 KiB

combo

#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cassert>
#include <tuple>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <unordered_set>
#include <unordered_map>

using namespace std;

typedef long long LL;
typedef vector<int> Vi;
typedef vector<bool> Vb;
typedef vector<vector<int>> Vii;

#define forR(i, n) for (int i = 0; i < (n); i++)

int press(string p);

string guess_sequence(int N) {

	// step 1: first
	char first;
	if (press("AB") >= 1) {
		if (press("A") == 1) first = 'A';
		else first = 'B';
	} else {
		if (press("X") == 1) first = 'X';
		else first = 'Y';
	}
	string s; s.append(1, first);

	set<char> keyset{ 'A','B','X','Y' }; keyset.erase(first);
	vector<char> ks(keyset.begin(), keyset.end());

	for (int i = 1; i <= N - 2; i++) {
		string q = s + ks[2] + ks[0] + s + ks[2] + ks[1] + s + ks[2] + ks[2] + s + ks[1];
		int r = press(q) - s.size();
		s.append(1, ks[r]);
	}
	if (s.size() < N) {
		assert(s.size() == N - 1);
		if (press(s + ks[0]) == N) return s + ks[0];
		if (press(s + ks[1]) == N) return s + ks[1];
		return s + ks[2];
	}
	return s;
}

#ifdef TEST_LOCAL
string ans = "BA";
int press(string p) {
	for (int i = ans.size(); i > 0; i--) {
		if (p.find(ans.substr(0, i)) != string::npos) {
			return i;
		}
	}
	return 0;
}
int main() {
	auto c = guess_sequence(ans.size());
	auto eq = c.compare(ans);

	return 0;
}
#endif

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:49:15: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   49 |  if (s.size() < N) {
      |      ~~~~~~~~~^~~
In file included from /usr/include/c++/10/cassert:44,
                 from combo.cpp:6:
combo.cpp:50:19: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   50 |   assert(s.size() == N - 1);
      |          ~~~~~~~~~^~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 95 / 95