2255. Count Prefixes of a Given String

#### QUESTION:

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
Explanation:
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
Explanation:
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.
``````

Constraints:

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

#### EXPLANATION:

easy的题目, 直接用hasprefix api即可.

#### SOLUTION:

``````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
}
}
``````