problem_199.py

def correct_braces(braces):
    # get rid of all initial closing braces
    i = 0
    while i < len(braces) and braces[i] == ')':
        i += 1
    braces = braces[i:]

    # base case for recursion
    if not braces:
        return ''

    # check for the first balanced group of braces
    open_braces = 0
    for i, brace in enumerate(braces):
        if brace == '(':
            open_braces += 1
        elif brace == ')':
            open_braces -= 1

        if not open_braces:
            break

    # if there is one, process the rest separately, else truncate the excess opening braces
    return braces[open_braces:] if open_braces else braces[:i+1] + correct_braces(braces[i+1:])


# Tests
assert correct_braces("()(()") == "()()"
assert correct_braces("()(()))") == "()(())"
assert correct_braces(")(())") == "(())"
assert correct_braces("())(") == "()"