Submission #750202

#	Time	Username	Problem	Language	Result	Execution time	Memory
750202		cheat_when_I_was_young	Combo (IOI18_combo)	C++17	Compilation error	0 ms	0 KiB

combo

#include<bits/stdc++.h>
#include "combo.h"
using namespace std;
string guess_sequence(int n) {
    int coins;
    string ans;
    coins = press("AB");
    if (coins) {
        coins = press("A");
        if (coins) ans[0] = 'A';
        else ans[0] = 'B';
    } else {
        coins = press("X");
        if (coins) ans[0] = 'X';
        else ans[0] = 'Y';
    }
    vector<string> d, e;
    vector<char> c = {'A', 'B', 'X', 'Y'};
    if (ans[0] == "A") {
        d = {"B", "XB", "XX", "XY"};
        e = {"Y", "B", "X"};
    } else if (ans[0] == "B") {
        d = {"A", "XA", "XX", "XY"};
        e = {"Y", "A", "X"};
    } else if (ans[0] == "X") {
        d = {"A", "YA", "YB", "YY"};
        e = {"B", "A", "Y"};
    } else if (ans[0] == "Y") {
        d = {"A", "XA", "XB", "XX"};
        e = {"B", "A", "X"};
    }
    while (ans.size() < n-1) {
        coins = press(ans + d[0] + ans + d[1] + ans + d[2] + ans + d[3]);
        ans += e[coins - ans.size()];
    }
    for (int i = 0; i < c.size();) {
        if (c[i] == ans[0]) c.erase(c.begin() + i);
        else ++i;
    }
    for (int i = 0; i < 2; ++i) {
        coins = press(ans + c[i]);
        if (coins) {
            ans += c[i];
            break;
        }
    }
    if (ans.size() < n) ans += c[2];
    return ans;
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:19:16: warning: comparison with string literal results in unspecified behavior [-Waddress]
   19 |     if (ans[0] == "A") {
combo.cpp:19:16: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
combo.cpp:22:23: warning: comparison with string literal results in unspecified behavior [-Waddress]
   22 |     } else if (ans[0] == "B") {
combo.cpp:22:23: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
combo.cpp:25:23: warning: comparison with string literal results in unspecified behavior [-Waddress]
   25 |     } else if (ans[0] == "X") {
combo.cpp:25:23: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
combo.cpp:28:23: warning: comparison with string literal results in unspecified behavior [-Waddress]
   28 |     } else if (ans[0] == "Y") {
combo.cpp:28:23: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
combo.cpp:32:23: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   32 |     while (ans.size() < n-1) {
      |            ~~~~~~~~~~~^~~~~
combo.cpp:36:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |     for (int i = 0; i < c.size();) {
      |                     ~~^~~~~~~~~~
combo.cpp:47:20: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   47 |     if (ans.size() < n) ans += c[2];
      |         ~~~~~~~~~~~^~~