Function is_valid

algorithms/stack/valid_parenthesis.py:17–39

Check if the bracket string is valid. Args: s: A string containing only bracket characters. Returns: True if the brackets are valid, False otherwise. Examples: >>> is_valid("()[]{}") True >>> is_valid("(]") False

(s: str)

def is_valid(s: str) -> bool:
    """Check if the bracket string is valid.

    Args:
        s: A string containing only bracket characters.

    Returns:
        True if the brackets are valid, False otherwise.

    Examples:
        >>> is_valid("()[]{}")
        True
        >>> is_valid("(]")
        False
    """
    stack: list[str] = []
    matching = {")": "(", "}": "{", "]": "["}
    for char in s:
        if char in matching.values():
            stack.append(char)
        elif char in matching and (not stack or matching[char] != stack.pop()):
                return False
    return not stack