Find common characters

Array Hash Table String

74.7% acceptance

Feb 25, 2026

4505

436

Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order.

Solution

Rust

Time O(n²)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn common_chars(words: Vec<String>) -> Vec<String> {
    let freq = |w: &str| -> [usize;26] {
      let mut f = [0usize;26];
      for b in w.bytes() { f[(b-b'a') as usize] += 1; }
      f
    };
    let mut min_f = freq(&words[0]);
    for w in &words[1..] {
      let f = freq(w);
      for i in 0..26 { min_f[i] = min_f[i].min(f[i]); }
    }
    let mut res = Vec::new();
    for i in 0..26 {
      for _ in 0..min_f[i] { res.push(((b'a'+i as u8) as char).to_string()); }
    }
    res
  }
}