Merkkijono

input/code.cpp: In function 'int main()':
input/code.cpp:13:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%hd", &n);
  ~~~~~^~~~~~~~~~~

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

int main(void) {
	char *str;
	uint16_t n, N, Ns, i, j;

	str = (char *)calloc(sizeof(char), UINT16_MAX);

	scanf("%hd", &n);

	N = (uint16_t)(pow(2, n) - 1);
	Ns = N / 2;


	memset(str, '0', Ns);
	*(str + Ns + 1) = '\0';

	//printf("size: %d, onesize: %d\n", N, Ns);

	for(i = n; i > 1; i--) {
		for(j = 0; j < pow(2, i-2); j++) {
			*(str + ((j+1) * ((uint16_t)pow(2, (n - i) + 1))) - 2 - (uint16_t)(pow(2, n-i) - 1)) = i + 'a' - 1;
			/*printf("%d = %d * %d - %d\tn = %d i = %d\n", ((j+1) * ((uint16_t)pow(2, (n - i)))) - 2 - (uint16_t)(pow(2, n-i + 1) - 1),
				(j+1), (((uint16_t)pow(2, (n - i) + 1))), 2 + (uint16_t)(pow(2, n-i) - 1),
				n, i);
			printf("%s\n", str);*/
		}
	}

	printf("%s%c%s\n", str, 'a', str);

	return 0;
}

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