Leetcode 1807. Evaluate the Bracket Pairs of a String

class Solution:
    def evaluate(self, s: str, knowledge: List[List[str]]) -> str:
        knowledge = {x[0]: x[1] for x in knowledge}
        n = len(s)
        i = 0
        result = ''
        while i < n:
            if s[i] == '(':
                key = ''
                i += 1
                while s[i] != ')':
                    key += s[i]
                    i += 1
                if key in knowledge:
                    result += knowledge[key]
                else:
                    result += '?'
            else:
                result += s[i]
            i += 1
        return result