README.md

1961. Check If String Is a Prefix of Array

Given a string s and an array of strings words, determine whether s is a prefix string of words.

A string s is a prefix string of words if s can be made by concatenating the first k strings in words for some positive k no larger than words.length.

Return true if s is a prefix string of words, or false otherwise.

Example 1:

Input: s = "iloveleetcode", words = ["i","love","leetcode","apples"]
Output: true
Explanation:
s can be made by concatenating "i", "love", and "leetcode" together.

Example 2:

Input: s = "iloveleetcode", words = ["apples","i","love","leetcode"]
Output: false
Explanation:
It is impossible to make s using a prefix of arr.

Constraints:

• 1 <= words.length <= 100
• 1 <= words[i].length <= 20
• 1 <= s.length <= 1000
• words[i] and s consist of only lowercase English letters.

Solutions (Python)

1. Solution

class Solution:
    def isPrefixString(self, s: str, words: List[str]) -> bool:
        if s == "":
            return True
        elif words == []:
            return False
        elif len(s) < len(words[0]):
            return False
        elif s[:len(words[0])] != words[0]:
            return False
        else:
            return self.isPrefixString(s[len(words[0]):], words[1:])