Formatted question description: https://leetcode.ca/all/1684.html

1684. Count the Number of Consistent Strings

Level

Easy

Description

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

Use a set to store all the letters in allowed. For each word in words, check whether all the letters in word are in the set. If this is the case, increase the counter by 1. Finally, return the counter.

class Solution {
    public int countConsistentStrings(String allowed, String[] words) {
        Set<Character> set = new HashSet<Character>();
        int length = allowed.length();
        for (int i = 0; i < length; i++)
            set.add(allowed.charAt(i));
        int count = 0;
        for (String word : words) {
            boolean flag = true;
            int wordLength = word.length();
            for (int i = 0; i < wordLength; i++) {
                if (!set.contains(word.charAt(i))) {
                    flag = false;
                    break;
                }
            }
            if (flag)
                count++;
        }
        return count;
    }
}

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