Python program to check matching of simple parentheses

Question

I am a Python newbie and I came across this exercise of checking whether or not the simple brackets \"(\", \")\" in a given string are matched evenly.

I have seen ex

Answer 1

An alternative to check for balanced nested parentheses:

def is_balanced(query: str) -> bool:
    # Alternative: re.sub(r"[^()]", "", query)
    query = "".join(i for i in query if i in {"(", ")"})
    while "()" in query:
        query = query.replace("()", "")
    return not query


for stmt in [
    "(()()()())",    # True
    "(((())))",      # True
    "(()((())()))",  # True
    "((((((())",     # False
    "()))",          # False
    "(()()))(()",    # False
    "foo",           # True
    "a or (b and (c or d)",  # False
    "a or (b and (c or d))"  # True
    "a or (b and (c or (d and e)))",  # True
]:
    print(stmt)
    print("Balanced:", is_balanced(stmt))
    print()

It works by:

1. Removing everything but parentheses
2. Recursively remove innermost parentheses pairs
3. If you're left with anything besides the empty string, the statement is not balanced. Otherwise, it is.