Merkkijono

#include <cmath>
#include <iostream>

using namespace std;

int main()
{
    int n;
    cin >> n;
    int c = (int) pow(2, n) - 1;
    char base = 'a' + n - 1;
    char curr = base;
    int a = 1;
    for(int i = 0; i < c; i++) {
        cout << curr;
        //cout << a << " ";

        if(i % 2 == 0) {
            curr -= a;
            //cout << -a << endl;
        } else {
            curr += a;
            //cout << a << endl;
            if(a != n - 1) {
                a++;
            } else {
                a--;
            }
        }
    }
    cout << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER