Java Data Structures Examine the following method explain what it does; write the pre and post conditions.

public static boolean balanced(String p)

{

final char LEFT_PAREN = '(';

final char RIGHT_PAREN = ')'

final char LEFT_BRACKET = '{';

final char RIGHT_BRACKET = '}';

CharStack s = new CharStack( ); int i; int length = p.length( ); char next;

for (i = 0; i < length; i++) { next = (char) p.charAt(i); switch (next) {

case LEFT_PAREN: case LEFT_BRACKET: s.push(next); break;

case RIGHT_PAREN: if (s.is_empty( ) || s.pop( ) != LEFT_PAREN) return false;

break; case RIGHT_BRACKET: if (s.is_empty( ) || s.pop( ) != LEFT_BRACKET) return false;

break; default: throw new IllegalArgumentException ("Illegal character: " + next);

}

}

return s.isEmpty( );

}

Why is it a bad idea to implement a singly linked list version of a queue with the head of the list as the rear of the queue?