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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.

Solution:

consistent 始终如一的，一贯的；持续的，连续的；固守的，坚持的；一致的，吻合的

class Solution {
    public int countConsistentStrings(String allowed, String[] words) {
        Set<Character> set = new HashSet<Character>();

        for (int i = 0; i < allowed.length(); i++){
            set.add(allowed.charAt(i));
        }

        int result = 0;
        for (String word: words){
            for (int i = 0; i < word.length(); i++){
                if (set.contains(word.charAt(i))){
                    if (i == word.length() - 1){
                        result++;
                    }
                    continue;
                }else {
                    break;
                }
            }
        }

        return result;

    }
}

// TC: O(n * k)
// SC: O(n)