[CodeSignal] Arcade - Smooth Sailing(14) reverseInParentheses

📄 Description

Write a function that reverses characters in (possibly nested) parentheses in the input string. Input strings will always be well-formed with matching ()s.

📌 Example

• For inputString = "(bar)", the output should be
  solution(inputString) = "rab"
• For inputString = "foo(bar)baz", the output should be
  solution(inputString) = "foorabbaz"
• For inputString = "foo(bar)baz(blim)", the output should besolution(inputString) = "foorabbazmilb"
• For inputString = "foo(bar(baz))blim", the output should be solution(inputString) = "foobazrabblim".
  👉 Because "foo(bar(baz))blim" becomes "foo(barzab)blim" and then "foobazrabblim".

📌 Input/Output

• [execution time limit] 4 seconds (py3)

• [input] string inputString

A string consisting of lowercase English letters and the characters ( and ). It is guaranteed that all parentheses in inputString form a regular bracket sequence.

Guaranteed constraints:
0 ≤ inputString.length ≤ 50.

• [output] string

Return inputString, with all the characters that were in parentheses reversed.

💻 My Submission

import re
def solution(inputString):
    start,end=[],[]
    
    for i, s in enumerate(inputString):
        if s=="(":
            start.append(i)
        elif s==")":
            end.append(i)
        if end:
            s, e=start.pop(), end.pop()
            old=inputString[s+1:e]
            new=inputString[s+1:e][::-1]
            inputString=inputString.replace(old,new)
        
    return re.sub('[\(\)]', "",inputString)

🚩 My Solution

🔵 Variables

start : queue that contains indexs of "(".
end: queue that contains indexs of ")".

🔴 Steps

1. If s is "(", append current index to start.
2. If s is ")", append current indext to end.
3. If end is not empty, it means you found character in paranthesis, so you reverse the substring. The right pair for end[-1] is start[-1]
4. Repeat above steps until you reach the last character of the string

🎈 Better Solutions(1)

def solution(s):
    for i in range(len(s)):
        if s[i] == "(":
            start = i
        if s[i] == ")":
            end = i
            return solution(s[:start] + s[start+1:end][::-1] + s[end+1:])
    return s

Solving the problem with recursion. YES, Now I see using recursion is more readable and cleaner.

References

• https://app.codesignal.com/arcade/intro/level-3/9DgaPsE2a7M6M2Hu6/solutions?solutionId=h5PsQ2fJPHRM5ZsHr