Leetcode 1961. Check If String Is a Prefix of Array

class Solution:
    def isPrefixString(self, s: str, words: List[str]) -> bool:
        n = len(s)
        i = 0
        for word in words:
            for j in range(len(word)):
                if s[i] == word[j]:
                    i += 1
                else:
                    return False
                if i == n:
                    return j == len(word) - 1
        return i == n

class Solution:
    def isPrefixString(self, s: str, words: List[str]) -> bool:
        n = len(s)
        i = 0
        for word in words:
            m = len(word)
            if s[i:i+m] == word:
                i += m
            else:
                return False
            if i == n:
                return True
        return i == n