[분할정복] 백준-칸토어 집합 C++ 4779번

https://www.acmicpc.net/problem/4779

#include <iostream>
#include <cmath>
#include <string>
using namespace std;

void change(int num, int index, string& dash)
{
	if (num == 1)
	{
		return;
	}

	num /= 3;
	string k(num, ' ');
	
	dash.replace(num + index, num, k);
	change(num, index, dash);
	change(num, index + 2 * num, dash);
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int N;
	while (cin >> N)
	{
		if (N == 0)
		{
			cout << '-' << '\n';
		}
		else
		{
			int c = pow(3, N);
			string dash(c, '-');
			change(dash.size(), 0, dash);
			cout << dash << endl;
		}
	}

	return 0;
}

// while(!cin.eof())는 안됐다. while(cin>>N)