1021-remove-outermost-parentheses.js

/**
 * 1021. Remove Outermost Parentheses
 * https://leetcode.com/problems/remove-outermost-parentheses/
 * Difficulty: Easy
 *
 * A valid parentheses string is either empty "", "(" + A + ")", or A + B, where A and B are valid
 * parentheses strings, and + represents string concatenation.
 * - For example, "", "()", "(())()", and "(()(()))" are all valid parentheses strings.
 *
 * A valid parentheses string s is primitive if it is nonempty, and there does not exist a way to
 * split it into s = A + B, with A and B nonempty valid parentheses strings.
 *
 * Given a valid parentheses string s, consider its primitive decomposition: s = P1
 * + P2 + ... + Pk, where Pi are primitive valid parentheses strings.
 *
 * Return s after removing the outermost parentheses of every primitive string in the primitive
 * decomposition of s.
 */

/**
 * @param {string} s
 * @return {string}
 */
var removeOuterParentheses = function(s) {
  let result = '';
  let depth = 0;

  for (const char of s) {
    if (char === '(') {
      if (depth > 0) result += char;
      depth++;
    } else {
      depth--;
      if (depth > 0) result += char;
    }
  }

  return result;
};