Submission #228361

#	Time	Username	Problem	Language	Result	Execution time	Memory
228361		Tehillah	Combo (IOI18_combo)	C++14	100 / 100	42 ms	752 KiB

combo

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

using ll = long long;

#define pb push_back
#define mkp make_pair
#define ff first
#define ss second
#define all(a) a.begin(), a.end()
#define sz(a) (int)(a.size())
#define clr(a, b) memset(a, b, sizeof(a))
#define REP(i, a, b) for(int i=(int)(a); i<(int)(b); ++i)
#define REPD(i, a, b) for(int i=(int)(a)-1; i>=(int)(b); --i)
#define FOR(it,c) for ( __typeof((c).begin()) it=(c).begin(); it!=(c).end(); it++ )

template<typename T> inline bool chkmin(T &a, const T &b) { return a > b ? a = b, 1 : 0; }
template<typename T> inline bool chkmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

string guess_sequence(int N) {
	string res = "";
	int ret = press("AB");
	if(ret >= 1) {
		ret = press("A");
		res += (ret == 1) ? 'A' : 'B';
	} else {
		ret = press("X");
		res += (ret == 1) ? 'X' : 'Y';
	}
	char c[] = {'A', 'B', 'X', 'Y'};
    char f[3];
	REP(i, 1, N) {
		string q = res;
		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;  
			}
			if(!done) f[2] = c[j];
		}
		if(sz(q) > 4*N) {
			ret = press(res + "A" + res + "B");
			if(ret >= i+1) {
				ret = press(res + "A");
				if(ret == i+1) 
					res += 'A';
				else
					res += 'B';
			} else {
				ret = press(res + "X");
				if(ret == i+1) 
					res += 'X';
				else
					res += 'Y';		
			}
		} else {
			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:53:5: warning: 'f[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   53 |     if(c[j] == f[k]) done = 1;
      |     ^~
combo.cpp:53:5: warning: 'f[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]

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