Submission #571157

#	Time	Username	Problem	Language	Result	Execution time	Memory
571157		sentheta	Combo (IOI18_combo)	C++17	100 / 100	37 ms	544 KiB

combo

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

#define V vector
#define rep(i,a,b) for(int i=(a); i<(b); i++)



#define sz (int)s.size()

string guess_sequence(int n){
	V<string> arr = {"A","B","X","Y"};


	string s;

	// find first char
	{
		int ax = press("AX"), bx = press("BX");

		if(ax && bx) s = "X";
		else if(ax) s = "A";
		else if(bx) s = "B";
		else s = "Y";
	}
	if(sz==n) return s;
	// put s[0] as last char
	{
		int i = 0;
		while(arr[i] != s) i++;
		swap(arr[i], arr[3]);
	}

	//cout << s << endl;

	rep(i,1,n-1){
		string t = s + arr[0] + arr[0]
					+ s + arr[0] + arr[1]
					+ s + arr[0] + arr[2]
					+ s + arr[1]
		;

		//cout << t << endl;
		int len = press(t);

		if(len==sz) s += arr[2];
		else if(len==sz+1) s += arr[1];
		else s += arr[0];
	}

	// last char
	string t = s + arr[0] + s + arr[1];
	if(press(t) > sz){
		t = s + arr[0];

		if(press(t) > sz) s += arr[0];
		else s += arr[1];
	}
	else s += arr[2];

	//assert(sz == n);
	return s;
}

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