LeetCode Entry

1002. Find Common Characters

05.06.2024 easy 2024 kotlin rust

Common letters in words

1002. Find Common Characters easy blog post substack youtube 2024-06-05_07-42.webp

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Problem TLDR

Common letters in words #easy

Intuition

We can count frequencies, then choose minimums for each char. Or do the reverse: for each char count minimum count in all words.

Approach

The frequencies code is faster, but the opposite approach is less verbose.

Complexity

  • Time complexity: \(O(n)\)

  • Space complexity: \(O(1)\), but can be O(n) to hold the result

Code


    fun commonChars(words: Array<String>) =
        ('a'..'z').map { c ->
            List(words.minOf { it.count { it == c } }) { "$c" }
        }.flatten()



    pub fn common_chars(words: Vec<String>) -> Vec<String> {
        ('a'..='z').map(|c| {
            let min_cnt = words.iter().map(|w|
                w.chars().filter(|a| *a == c).count()).min();
            vec![format!("{c}"); min_cnt.unwrap_or(0)]
        }).flatten().collect()
    }