Submission #713595

#	Time	Username	Problem	Language	Result	Execution time	Memory
713595		DennisTran	Combo (IOI18_combo)	C++17	100 / 100	41 ms	488 KiB

combo

#pragma GCC optimize("O2")
#pragma GCC target("avx,avx2,fma")
#include "combo.h"
#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FOD(i, a, b) for (int i = (a); i >= (b); i--)
#define REP(i, n) for (int i = 0; i < (n); i++)
#define ALL(x) (x).begin(), (x).end()
#define TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }

using namespace std;

const int MAXN = 2e5 + 5;


string guess_sequence(int N) {
    if (N == 1) {
        if (press("A")) return "A";
        if (press("B")) return "B";
        if (press("X")) return "X";
        return "Y";
    }

    string T = "", S = "";
    if (press("AB")) {
        if (press("A")) T += 'A';
        else T += 'B';
    } else {
        if (press("X")) T += 'X';
        else T += 'Y';
    }

    for (char c : {'A', 'B', 'X', 'Y'}) {
        if (c == T[0]) continue;
        T += c;
    }

    S = T[0];
    while (S.size() < N - 1) {
        string ask = S + T[1] + T[1] + S + T[1] + T[2] + S + T[1] + T[3] + S + T[2];
        int p = press(ask);
        if (p - 2 == S.size()) S += T[1];
        else if (p - 1 == S.size()) S += T[2];
        else S += T[3];
    }

    if (press(S + T[1]) == N) return S + T[1];
    else if (press(S + T[2]) == N) return S + T[2];
    else return S + T[3];
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:40:21: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   40 |     while (S.size() < N - 1) {
      |            ~~~~~~~~~^~~~~~~
combo.cpp:43:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |         if (p - 2 == S.size()) S += T[1];
      |             ~~~~~~^~~~~~~~~~~
combo.cpp:44:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         else if (p - 1 == S.size()) S += T[2];
      |                  ~~~~~~^~~~~~~~~~~

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