leetcode-856

856. 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:

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Input: "()"
Output: 1

Example 2:

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Input: "(())"
Output: 2

Example 3:

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Input: "()()"
Output: 2

Example 4:

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

Note:

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

Analyse

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int scoreOfParentheses(string S) {
        int score = 0;
        int level = 0;
        char last = 0;

        for (int i = 0; i < S.length(); i++)
        {
            if (S[i] == '(')
            {
                level++;
            }
            else if (S[i] == ')')
            {
                level--;

                if (last == '(')
                {
                    score += 1 << level;
                }
            }

            last = S[i];
        }

        return score;
    }