2255. Count Prefixes of a Given String


You are given a string array words and a string s, where words[i] and s comprise only of lowercase English letters.

Return the number of strings in words that are a prefix of s.

A prefix of a string is a substring that occurs at the beginning of the string. A substring is a contiguous sequence of characters within a string.

Example 1:

Input: words = ["a","b","c","ab","bc","abc"], s = "abc"
Output: 3
The strings in words which are a prefix of s = "abc" are:
"a", "ab", and "abc".
Thus the number of strings in words which are a prefix of s is 3.

Example 2:

Input: words = ["a","a"], s = "aa"
Output: 2
Both of the strings are a prefix of s. 
Note that the same string can occur multiple times in words, and it should be counted each time.


1 <= words.length <= 1000
1 <= words[i].length, s.length <= 10
words[i] and s consist of lowercase English letters only.


easy的题目, 直接用hasprefix api即可.


class Solution {
    func countPrefixes(_ words: [String], _ s: String) -> Int {
        var result:Int = 0
        for word in words {
            if s.hasPrefix(word) {
                result += 1
        return result