Submission #661158

#	Time	Username	Problem	Language	Result	Execution time	Memory
661158		NekoRolly	Combo (IOI18_combo)	C++17	100 / 100	30 ms	560 KiB

combo

#include<bits/stdc++.h>
#include "combo.h"
using namespace std;

vector<char> v;

string S(char a,char b){ string s;
	s += v[a], s += v[b];
	return s;
}

string guess_sequence(int n){ string s;
	if (press("AB")){
		if (press("A")) s += 'A';
		else s += 'B';
	}
	else{
		if (press("X")) s += 'X';
		else s += 'Y';
	}

	if (n == 1) return s;

	for (char c : {'A', 'B', 'X', 'Y'})
		if (c != s[0]) v.push_back(c);

	for (int i=1; i<n-1; i++){ string t = s;
		t += S(0, 0), t += s, t += S(0, 1), t += s;
		t += S(0, 2), t += s, t += v[1];
		int x = press(t);
		if (x == 2+s.size()) s += v[0];
		else if (x == 1+s.size()) s += v[1];
		else s += v[2];
	}

	if (press(s + v[0]) == n) s += v[0];
	else if (press(s + v[1]) == n) s += v[1];
	else s += v[2];

	return s;
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:31:9: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |   if (x == 2+s.size()) s += v[0];
      |       ~~^~~~~~~~~~~~~
combo.cpp:32:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |   else if (x == 1+s.size()) s += v[1];
      |            ~~^~~~~~~~~~~~~

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