1190. Reverse Substrings Between Each Pair of Parentheses

ou are given a string s that consists of lower case English letters and brackets.

Reverse the strings in each pair of matching parentheses, starting from the innermost one.

Your result should not contain any brackets.

Example 1:

Input: s = "(abcd)"
Output: "dcba"

Example 2:

Input: s = "(u(love)i)"
Output: "iloveu"
Explanation: The substring "love" is reversed first, then the whole string is reversed.

Example 3:

Input: s = "(ed(et(oc))el)"
Output: "leetcode"
Explanation: First, we reverse the substring "oc", then "etco", and finally, the whole string.

Example 4:

Input: s = "a(bcdefghijkl(mno)p)q"
Output: "apmnolkjihgfedcbq"

Solution

Approach 1: using a stack.

Code (Python)

Approach 1:

    def reverseParentheses(self, s: str) -> str:
        stack = []
        deque = []
        for char in s:
            if char != ')':
                stack.append(char)
            else:
                while stack:
                    popped = stack.pop()
                    if popped != '(':
                        deque.append(popped)
                    else:
                        break
                # get the letters popped back to the stack in order
                for letter in deque:
                    stack.append(letter)
                deque = []
        return ''.join(stack)

Code (C++)

Approach 1:

Approach 2: