C/C++ :: Drawing Array But Breaks Depending On Size

I am working on a code and first i need to initialize the array depending on the size (min size 3x3, maximum size 9x9). The initialized array will descend in order. Note that it seems like a simple code and seems to work for any size from 3x3 to 7x7, but for some reason i get a strange output in the last few rows for 8x8 and 9x9. Not sure why. The second part to my problem is the very last digit of 0. I did hard code to define it but i would like to make it a character like an underscore...what is the easy way to do this?

* Implements the Game of Fifteen (generalized to d x d).
*
* Usage: ./fifteen d
*
* whereby the board's dimensions are to be d x d,
* where d must be in [MIN,MAX]
*
* Note that usleep is obsolete, but it offers more granularity tha sleep and is simpler to use than nanosleep; `man usleep` for more.

#define _XOPEN_SOURCE 500

#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
// board's minimal dimension
#define MIN 3

[Code] .....