Mismatched Brackets - https://algospot.com/judge/problem/read/BRACKETS2

open_stack.py

class Stack:
    def __init__(self):
        self.storage = []

    def is_empty(self):
        return len(self.storage) == 0

    def push(self, value):
        self.storage.append(value)

    def pop(self):
        return self.storage.pop()

    def top(self):
        return self.storage[-1]


def well_matched(string_):
    opening = ['(', '{', '[']
    closing = [')', '}', ']']
    open_stack = Stack()
    for ch in string_:
        if ch in opening:
            open_stack.push(ch)
        else:
            if open_stack.is_empty():
                return 'NO'
            top = open_stack.top()
            if opening.index(top) != closing.index(ch):
                return 'NO'
            open_stack.pop()
    if open_stack.is_empty():
        return 'YES'
    return 'NO'


if __name__ == '__main__':
    n = int(raw_input())
    for i in range(n):
        string_  = raw_input()
        print well_matched(string_)