Given a balanced parentheses string `s`, return the score of the string.

The score of a balanced parentheses string is 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: s = "()"
    Output: 1

Example 2:

    Input: s = "(())"
    Output: 2

Example 3:

    Input: s = "()()"
    Output: 2

Constraints:

- `2 <= s.length <= 50`
- `s` consists of only `'('` and `')'`.
- `s` is a balanced parentheses string.