Submission #362153

#	Time	Username	Problem	Language	Result	Execution time	Memory
362153		penguinhacker	Combo (IOI18_combo)	C++14	100 / 100	53 ms	548 KiB

combo

#include <string>
#include <vector>
#include <assert.h>
using namespace std;

int press(string p);

string guess_sequence(int n) {
	string ans;
	if (press("AB") > 0) {
		if (press("A")) ans = "A";
		else ans = "B";
	}
	else {
		if (press("X")) ans = "X";
		else ans = "Y";
	}
	assert((int)ans.size() == 1);
	if (n == 1) return ans;
	vector<char> v;
	if (ans != "A") v.push_back('A');
	if (ans != "B") v.push_back('B');
	if (ans != "X") v.push_back('X');
	if (ans != "Y") v.push_back('Y');
	assert(v.size() == 3);
	for (int i = 1; i < n - 1; ++i) {
		string s = ans + v[0] + v[0] + ans + v[0] + v[1] + ans + v[0] + v[2] + ans + v[1];
		assert((int)s.size() <= 4 * n);
		int x = press(s);
		if (x == i) ans += v[2];
		else if (x == i + 1) ans += v[1];
		else if (x == i + 2) ans += v[0];
		else assert(0);
	}
	assert((int)ans.size() == n - 1);
	if (press(ans + v[0]) == n) ans += v[0];
	else if (press(ans + v[1]) == n) ans += v[1];
	else ans += v[2];
	assert((int)ans.size() == n);
	return ans;
}

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