leetcode1961. 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: trueExplanation:s can be made by concatenating "i", "love", and "leetcode" together.

Example 2:

Input: s = "iloveleetcode", words = ["apples","i","love","leetcode"]Output: falseExplanation: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.

Runtime: 3 ms, faster than 30.70% of Java online submissions for Check If String Is a Prefix of Array.

Memory Usage: 43.9 MB, less than 6.17% of Java online submissions for Check If String Is a Prefix of Array.

用stringbuilder 遍历数组的字符，每次跟选定的字符串比对是否一样，即可确认prefix是不是字符串s了。