Valid_Parentheses.py

"""
@author - Anirudh Sharma
"""


def isValid(s: str) -> bool:
    # Stack for left symbols
    leftSymbols = []
    # Loop for each character of the string
    for c in s:
        # If left symbol is encountered
        if c in ['(', '{', '[']:
            leftSymbols.append(c)
        # If right symbol is encountered
        elif c == ')' and len(leftSymbols) != 0 and leftSymbols[-1] == '(':
            leftSymbols.pop()
        elif c == '}' and len(leftSymbols) != 0 and leftSymbols[-1] == '{':
            leftSymbols.pop()
        elif c == ']' and len(leftSymbols) != 0 and leftSymbols[-1] == '[':
            leftSymbols.pop()
        # If none of the valid symbols is encountered
        else:
            return False
    return leftSymbols == []


if __name__ == '__main__':
    print(isValid("()"))
    print(isValid("()[]{}"))
    print(isValid("(]"))
    print(isValid("([)]"))
    print(isValid("{[]}"))