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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
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.

Solutions (Rust)

1. Solution

impl Solution {
    pub fn count_prefixes(words: Vec<String>, s: String) -> i32 {
        words
            .iter()
            .filter(|word| s.starts_with(word.as_str()))
            .count() as i32
    }
}