Calculates the hash code for Strings, using the x$=31*$x $+$ y pattern.

$*$ Follow the specification in the String.hashCode$()$ method in the Java API.

$*$ Note that the hashcode can overflow the max integer, so it can be

$*$ negative. Later, in another method, you'll need to account for a negative

$*$ hashcode by adding Integer.MAX$\_$VALUE $+1$ before you mod by the capacity

$*($table size$)$ to get the index.

$*$

$*$ This method is NOT the place to calculate the index though.

$*$

$*$ @param item

$*$ @return The hash code for this String

$*/$