Submission #903897

#	Time	Username	Problem	Language	Result	Execution time	Memory
903897		zhasyn	Combo (IOI18_combo)	C++17	Compilation error	0 ms	0 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
using namespace std;
#define F first
#define S second
typedef long long ll;
#define pii pair <int, int>
#define pll pair <ll, ll>
typedef long double ld;
const ll N = 2 * 1e5 + 10, len = 316;
const ll mod = 1e9 + 7;

ll um(ll a, ll b){
	return ((1LL * a * b) % mod + mod) % mod;
}
ll subr(ll a, ll b){
	return ((1LL * a - b) % mod + mod) % mod;
}
string guess_sequence(int n){
	string s = "ABXY";
	int fir;
	if(press("AB") >= 1){
		if(press("A") == 1) fir = 0;
		else fir = 1;
	} else{
		if(press("X") == 1) fir = 2;
		else fir = 3;
	}
	string ans = s[fir];
	for(int i = 1; i < n; i++){
		int cnt = 0;
		for(int j = 0; j < 4; j++){
			if(j == fir) continue;
			if(cnt == 2){
				ans += s[j];
				break;
			}
			int k = press(ans + s[j]);
			cnt++;
			if(k == i + 1){
				ans += s[j];
				break;
			}
		}
	}
	return ans;
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:31:20: error: conversion from '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   31 |  string ans = s[fir];
      |                    ^