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 <= 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.

Problem Summary #

Given a string allowed consisting of distinct characters and an array of strings words. If every character of a string is in allowed, then this string is called a consistent string.

Return the number of consistent strings in the words array.

Solution Approach #

• Easy problem. First convert allowed into a map. For each word in the words array, check every character in the map. If all characters exist, increment res. If there is a character that does not exist, do not increment it. Finally, output res.

Code #

package leetcode

func countConsistentStrings(allowed string, words []string) int {
	allowedMap, res, flag := map[rune]int{}, 0, true
	for _, str := range allowed {
		allowedMap[str]++
	}
	for i := 0; i < len(words); i++ {
		flag = true
		for j := 0; j < len(words[i]); j++ {
			if _, ok := allowedMap[rune(words[i][j])]; !ok {
				flag = false
				break
			}
		}
		if flag {
			res++
		}
	}
	return res
}