LeetCode Entry

1684. Count the Number of Consistent Strings

12.09.2024 easy 2024 kotlin rust

Count words with allowed characters

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Problem TLDR

Count words with allowed characters #easy

Intuition

There are total of 26 characters, check them.

Approach

  • we can use a HashSet
  • we can use a bit mask

Complexity

  • Time complexity: \(O(n)\)

  • Space complexity: \(O(1)\)

Code


    fun countConsistentStrings(allowed: String, words: Array<String>) =
        words.count { it.all { it in allowed }}



    pub fn count_consistent_strings(allowed: String, words: Vec<String>) -> i32 {
        let set: HashSet<_> = allowed.bytes().collect();
        words.iter().filter(|w| w.bytes().all(|b| set.contains(&b))).count() as _
    }



    int countConsistentStrings(string allowed, vector<string>& words) {
        auto bits = [](string w) {
            int mask = 0; for (int i = 0; i < w.length(); i++)
                mask |= 1 << (w[i] - 'a');
            return mask;
        };
        int mask = bits(allowed);
        return std::count_if(words.begin(), words.end(),
            [mask, &bits](string w){return (mask | bits(w)) == mask;});
    }