[백준] 4246번 To and Fro

https://www.acmicpc.net/problem/4246

4246번: To and Fro

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

int main() {
	while (true) {
		int n;
		cin >> n;
		if (n == 0) break;
		string s;
		cin >> s;
		vector<vector<char>> arr(s.size() / n, vector<char>(n));
		int index = 0;
		for (int i = 0; i < s.size() / n; i++) {
			if (i % 2 == 0) {
				for (int j = 0; j < n; j++) {
					arr[i][j] = s[index++];
				}
			}
			else {
				for (int j = n - 1; j >= 0; j--) {
					arr[i][j] = s[index++];
				}
			}
		}
		for (int j = 0; j < n; j++) {
			for (int i = 0; i < s.size() / n; i++) {
				cout << arr[i][j];
			}
		}
		cout << '\n';
	}
	return 0;
}