README.md

1684. Count the Number of Consistent Strings

You are given a string allowed consisting of distinct characters and an array of strings words. A string is consistent if all characters in the string appear in the string allowed.

Return the number of consistent strings in the array words.

Example 1:

Input: allowed = "ab", words = ["ad","bd","aaab","baa","badab"]
Output: 2
Explanation: Strings "aaab" and "baa" are consistent since they only contain characters 'a' and 'b'.

Example 2:

Input: allowed = "abc", words = ["a","b","c","ab","ac","bc","abc"]
Output: 7
Explanation: All strings are consistent.

Example 3:

Input: allowed = "cad", words = ["cc","acd","b","ba","bac","bad","ac","d"]
Output: 4
Explanation: Strings "cc", "acd", "ac", and "d" are consistent.

Constraints:

• 1 <= words.length <= 104
• 1 <= allowed.length <= 26
• 1 <= words[i].length <= 10
• The characters in allowed are distinct.
• words[i] and allowed contain only lowercase English letters.

Solutions (Rust)

1. Solution

impl Solution {
    pub fn count_consistent_strings(allowed: String, words: Vec<String>) -> i32 {
        let allowed = allowed.bytes().fold(0, |ac, c| ac | (1 << (c - b'a')));

        words
            .iter()
            .filter(|word| word.bytes().all(|c| allowed & (1 << (c - b'a')) != 0))
            .count() as i32
    }
}