Score of Parentheses

Description

Given a balanced parentheses string S, compute the score of the string based on the following rule:

• () has score 1
• AB has score A + B, where A and B are balanced parentheses strings.
• (A) has score 2 * A, where A is a balanced parentheses string.

 

Example 1:

Input: "()"
Output: 1

Example 2:

Input: "(())"
Output: 2

Example 3:

Input: "()()"
Output: 2

Example 4:

Input: "(()(()))"
Output: 6

 

Note:

1. S is a balanced parentheses string, containing only ( and ).
2. 2 <= S.length <= 50

Solution(javascript)

/**
 * @param {string} S
 * @return {number}
 */
const scoreOfParentheses = function (S) {
  const stack = []
  for (const c of S) {
    stack.push(c)
    while (stack[stack.length - 1] === ')') {
      stack.pop() // ")"
      if (stack[stack.length - 1] === '(') {
        stack.pop() // "("
        stack.push(1)
      } else {
        let num = stack.pop()
        while (stack[stack.length - 1] >= 1) {
          num += stack.pop()
        }
        stack.pop() // "("
        stack.push(2 * num)
      }
    }
  }
  return stack.reduce((acc, a) => acc + a, 0)
}