Merkkijono

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#pragma GCC diagnostic ignored "-Wunused-result"

unsigned long function(unsigned long x) { return x*x-x+1; }

int main()
{
    unsigned long n;

    scanf("%lu", &n);

    unsigned long length = function(n);
    char* string = (char*)malloc(length + 1);
    string[0] = 'a';
    string[length] = 0;

    unsigned long index = 1;

    for(unsigned long i = 1; i < n; i++)
    {
        string[index] = 'a';
        for(unsigned long j = 0; j < index; j++) { string[j]++; }
        memcpy(string + index + 1, string, index);

        index = function(i + 1) + 1;
    }

    printf("%s", string);

}

#pragma GCC diagnostic pop

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

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