balancedParentheses.py

def getBalancedParens(pairs, openRem=None, closeRem=None, current='', indent=0):
    if openRem is None:
        openRem = pairs
    if closeRem is None:
        closeRem = pairs

    print('.' * indent, end='')
    print('Start of pairs=' + str(pairs) + ', openRem=' + str(openRem) +
    ', closeRem=' + str(closeRem) + ', current="' + current + '"')
    if openRem == 0 and closeRem == 0:
        # BASE CASE
        print('.' * indent, end='')
        print('1st base case. Returning ' + str([current]))
        return [current]

    # RECURSIVE CASE
    results = []
    if openRem > 0:
        print('.' * indent, end='')
        print('Adding open parenthesis.')
        results.extend(getBalancedParens(pairs, openRem - 1, closeRem,
        current + '(', indent + 1))
    if closeRem > openRem:
        print('.' * indent, end='')
        print('Adding close parenthesis.')
        results.extend(getBalancedParens(pairs, openRem, closeRem - 1,
        current + ')', indent + 1))

    # BASE CASE
    print('.' * indent, end='')
    print('2nd base case. Returning ' + str(results))
    return results

print('All combinations of 2 balanced parentheses:')
print('Results:', getBalancedParens(2))