Submission #713105

#	Time	Username	Problem	Language	Result	Execution time	Memory
713105		hoainiem	Combo (IOI18_combo)	C++14	Compilation error	0 ms	0 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string vt, st;
pair<int, int>ds[3]{{0, 1}, {0, 2}, {1, 2}};
string s[3];
int k, mask;
string operator+(string a, char b){
    a.push_back(b);
    return a;
}
string operator+(char a, char b){
    string res;
    res.push_back(a);
    res.push_back(b);
    return res;
}
std::string guess_sequence(int n) {
    string ans;
    srand(time(NULL));
    k = press("AB");
    if (k == 2)
        ans = "AB";
    else{
        if (k == 1){
            if (press("A"))
                ans = "A";
            else
                ans = "B";
        }
        else{
            if (press("X"))
                ans = "X";
            else
                ans = "Y";
        }
    }
    vt = {'A', 'B', 'X', 'Y'};
    for (int i = 0; i < 4; i++)
        if (vt[i] == ans[0]){
            vt.erase(vt.begin() + i);
            break;
        }
    mask = vt[0] ^ vt[1] ^ vt[2];
    char a = vt[0], b = vt[1], c = vt[2];
    while (true){
        int sz = ans.size();
        if (n - (int)ans.size() == 1){
            if (press(ans + a) == n)
                return ans + a;
            else{
                if(press(ans + b) == n)
                    return ans + b;
                return ans + c;
            }
        }
        int op = press(ans + a + ans + b + a + ans + b + b + ans + b + c);
        if (op == sz)
            ans = ans + c;
        else{
            if (op - sz == 1)
                ans = ans + a;
            else
                ans = ans + b;
        }
    }
    return ans;
}

Compilation message (stderr)

combo.cpp:12:8: error: 'std::string operator+(char, char)' must have an argument of class or enumerated type
   12 | string operator+(char a, char b){
      |        ^~~~~~~~