How to balance parenthesis recursively

Question

I\'m working on some code to balance parenthesis, this question proved most useful for the algorithm.

I implemented it in my first language (PHP) but I\'m learning Scala

Answer 1

It seems we are attending the same course. my solution:

def balance(chars: List[Char]): Boolean = 
doBalance(chars, 0) == 0;
def doBalance(chars: List[Char], parenthesisOpenCount: Int): Int =
if(parenthesisOpenCount <0) -100;
else
if(chars.isEmpty) parenthesisOpenCount
else
  chars.head match {
  case '(' => return doBalance(chars.tail, parenthesisOpenCount+1) 
  case ')' => return doBalance(chars.tail, parenthesisOpenCount-1)
  case _ => return doBalance(chars.tail, parenthesisOpenCount)
}