Merkkijono

input/code.cpp: In function 'int main()':
input/code.cpp:14:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int x = 0; x < s.length(); x++) {
                   ~~^~~~~~~~~~~~

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

int main()
{
	const char a[] = { 'b', 'c', 'd', 'e','f','g','h', 'i', 'j','k','l','m','n','o','p','q','r','s','t' };
	int n;
	cin >> n;

	string s = "a";
	for (int i = 0; i < n - 1; i++) {
		string t = "";
		for (int x = 0; x < s.length(); x++) {
			t.push_back(a[i]);
			t.push_back(s[x]);
		}
		t.push_back(a[i]);
		s = t;
	}
	cout << s;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED