$/**$

$*$ First check whether it's a valid move to put the given number at the given position,

$*$ and then put the given number into the board if and only if it's a valid move.

$*$

$*$ @param row The row you want to fill number

$*$ @param col The column you want to fill number

$*$ @param val The number you want to fill in

$*$ @param board The current Sudoku board

$*$ @param original The boolean array parallel to board, representing whether

$*$ there's a pre$-$existing number for each position

$*$ @return $0$ if either board or original is null

$*-1$ if the row is out of valid range $(0$~$8)$

$*-2$ if the column is out of valid range $(0$~$8)$

$*-3$ if val is out of valid range $(1$~$9$ and Config.EMPTY$)$

$*-4$ if the number at the current position $($row$,$ col$)$ is pre$-$existing

$*-5$ if there's a conflict in the board after filling in val at $($row$,$ col$)$

$*$ Note: remember to call checkConflictForBoard for this

$*1$ if there's a success filling in the number. If and only if in

$*$ this case, should you actually place the number into the board.

$*$

$*$ Note: You need to check the conditions exactly in the above order.

$*/$

public static int fillNumber$($int row, int col, int val, int$[][]$ board, boolean$[][]$ original$)\{$

return $0$;

$\}$