Codility Lesson 7 Brackets Python

Question

A string S consisting of N characters is considered to be properly nested if any of the following conditions is true:

S is empty;
S has the form "(U)" or "[U]" or "{U}" where U is a properly nested string;
S has the form "VW" where V and W are properly nested strings.
For example, the string "{[()()]}" is properly nested but "([)()]" is not.

Write a function:

def solution(S)

that, given a string S consisting of N characters, returns 1 if S is properly nested and 0 otherwise.

For example, given S = "{[()()]}", the function should return 1 and given S = "([)()]", the function should return 0, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..200,000];
string S is made only of the following characters: '(', '{', '[', ']', '}' and/or ')'.

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Answer

from collections import deque

def solution(S):
    S_deque = deque()
    for s in S:
        if s in '{[(':
            S_deque.append(s)
        else:
            if len(S_deque) == 0:
                return 0
            pair = S_deque.pop()
            if s == '}':
                if pair != '{':
                    return 0
            elif s == ']':
                if pair != '[':
                    return 0
            else:
                if pair != '(':
                    return 0
    if len(S_deque) > 0:
        return 0
    return 1