1190. Reverse Substrings Between Each Pair of Parentheses

Description

You 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.

 

Constraints:

• 1 <= s.length <= 2000
• s only contains lower case English characters and parentheses.
• It is guaranteed that all parentheses are balanced.

 

Solutions

Solution: Stack

• Time complexity: O(n)
• Space complexity: O(n)

 

JavaScript

/**
 * @param {string} s
 * @return {string}
 */
const reverseParentheses = function (s) {
  const n = s.length;
  const stack = [];
  const pairMap = new Map();

  for (let index = 0; index < n; index++) {
    const char = s[index];

    if (char === '(') stack.push(index);
    if (char === ')') {
      const pair = stack.pop();

      pairMap.set(index, pair);
      pairMap.set(pair, index);
    }
  }

  let move = 1;
  let result = '';

  for (let index = 0; index < n; index += move) {
    const char = s[index];

    if (char === '(' || char === ')') {
      index = pairMap.get(index);
      move = -move;
      continue;
    }
    result += char;
  }
  return result;
};