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.
思路一：建立 map 映射，最后遍历即可
public int countConsistentStrings(String allowed, String[] words) {
int[] arr = new int[26];
for (char c : allowed.toCharArray()) {
arr[c - 'a'] = 1;
}
int count = 0;
out:
for (String word : words) {
for (char c : word.toCharArray()) {
if (arr[c - 'a'] == 0) continue out;
}
count++;
}
return count;
}