https://github.com/emahtab/repeated-dna-sequences

https://github.com/emahtab/repeated-dna-sequences

leetcode repeated-substring

Last synced: 1 day ago
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• Host: GitHub
• URL: https://github.com/emahtab/repeated-dna-sequences
• Owner: eMahtab
• Created: 2024-10-07T15:08:50.000Z (4 months ago)
• Default Branch: main
• Last Pushed: 2025-01-21T06:39:46.000Z (5 days ago)
• Last Synced: 2025-01-21T07:27:44.148Z (5 days ago)
• Topics: leetcode, repeated-substring
• Homepage:
• Size: 1.95 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Repeated DNA Sequences

## https://leetcode.com/problems/repeated-dna-sequences

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.

```java

Example 1:

Input: s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT"

Output: ["AAAAACCCCC","CCCCCAAAAA"]

Example 2:

Input: s = "AAAAAAAAAAAAA"

Output: ["AAAAAAAAAA"]

``` 

### Constraints:

1. 1 <= s.length <= 105

2. s[i] is either 'A', 'C', 'G', or 'T'.

## Implementation 1 :

```java

class Solution {

    public List findRepeatedDnaSequences(String s) {

        List result = new ArrayList<>();

        if(s.length() <= 10)

          return result;

        Map map = new HashMap<>();  

        for(int i = 0; i <= s.length() - 10; i++) {

            String substr = s.substring(i, i+10);

            int occurrence = map.getOrDefault(substr, 0);

            map.put(substr, occurrence + 1); 

        }

        for(String str : map.keySet()) {

            if(map.get(str) > 1)

             result.add(str);

        }

        return result;  

    }

}

```

## Implementation 1a :

```java

class Solution {

    public List findRepeatedDnaSequences(String s) {

        if(s == null || s.length() < 11)

          return new ArrayList<>();

        Map map = new HashMap<>();

        map.put(s.substring(0, 10), 1);

        int left = 1;

        for(int i = 10; i < s.length(); i++) {

            String str = s.substring(left, i+1);

            int occurrences = map.getOrDefault(str, 0);

            map.put(str, occurrences+1);

            left++;

        }  

        return map.entrySet()

                  .stream()

                  .filter(entry -> entry.getValue() > 1)

                  .map(entry -> entry.getKey())

                  .collect(Collectors.toList());

    }

}

```