Submission #228367

#	Time	Username	Problem	Language	Result	Execution time	Memory
228367		Tehillah	Combo (IOI18_combo)	C++14	100 / 100	40 ms	696 KiB

combo

#include <string>
#include "combo.h"
using namespace std;
#define sz(a) (int)(a.size())
#define REP(i, a, b) for(int i=(int)(a); i<(int)(b); ++i)
 
string guess_sequence(int N) {
	string res = "";
	char c[] = {'A', 'B', 'X', 'Y'}, f[3];	
	REP(i, 0, N) {
		string q = res;
		if(sz(res) > 0) {
			REP(j, 0, 4) {
				if(res[0] != c[j]) {
					if(sz(q) > sz(res)) {
						f[1] = c[j];
						REP(k, 0, 4) if(c[k] != res[0]) q += res + c[j] + c[k]; 
						break;
					}
					else q += c[j], f[0] = c[j];
				} 
			}
			REP(j, 0, 4) {
				if(c[j] == res[0]) continue;
				int done = 0;
				REP(k, 0, 2) if(c[j] == f[k]) {done = 1; break;}
				if(!done) {f[2] = c[j]; break;}
			}
		}
		if(sz(q) > 4*N || i == 0) {
			if(press(res + "A" + res + "B") >= i+1) res += ((press(res + "A") == i+1) ? 'A' : 'B');
			else res += ((press(res + "X") == i+1) ? 'X' : 'Y');
		} else {
			int ret = press(q);
			if(ret == i+1) res += f[0];	
			else if(ret == i+2) res += f[1];
			else res += f[2];
		}	
	}
	return res;
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:26:18: warning: 'f[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   26 |     REP(k, 0, 2) if(c[j] == f[k]) {done = 1; break;}
      |                  ^~
combo.cpp:26:18: warning: 'f[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]

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