Repeated dna sequences

Hash Table String Bit Manipulation Sliding Window Rolling Hash Hash Function

52.9% acceptance

Jan 12, 2026

3609

570

The DNA sequence is composed of a series of nucleotides abbreviated as 'A', 'C', 'G', and 'T'. For example, "ACGAATTCCG" is a DNA sequence. When studying DNA, it is useful to identify repeated sequences within the DNA. Given a string s that represents a DNA sequence, return all the 10-letter-long sequences (substrings) that occur more than once in a DNA molecule. You may return the answer in any order.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn find_repeated_dna_sequences(s: String) -> Vec<String> {
    if s.len() < 10 {
      return vec![];
    }
    
    let mut seen = std::collections::HashSet::new();
    let mut repeated = std::collections::HashSet::new();
    
    for i in 0..=s.len() - 10 {
      let substring = &s[i..i + 10];
      if !seen.insert(substring) {
        repeated.insert(substring.to_string());
      }
    }
    
    repeated.into_iter().collect()
  }
}