1684. Count the Number of Consistent Strings

Problem

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 <= 10^4

• 1 <= allowed.length <= 26

• 1 <= words[i].length <= 10

• The characters in allowed are distinct.

• words[i] and allowed contain only lowercase English letters.

Solution (Java)

class Solution {
    public int countConsistentStrings(String allowed, String[] words) {
        int alwd = 0;
        int res = 0;
        for (int i = 0; i < allowed.length(); ++i) {
            alwd |= 1 << allowed.charAt(i);
        }
        for (String word : words) {
            int b = 0;
            for (int j = 0; j < word.length(); ++j) {
                b |= 1 << word.charAt(j);
            }
            if ((alwd | b) == alwd) {
                ++res;
            }
        }
        return res;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).