Repeated DNA Sequences

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Repeated DNA Sequences Total Accepted: 8816 Total Submissions: 47451 My Submissions Question Solution
All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: “ACGAATTCCG”. When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.

Write a function to find all the 10-letter-long sequences (substrings) that occur more than once in a DNA molecule.

For example,

Given s = “AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT”,

Return:
[“AAAAACCCCC”, “CCCCCAAAAA”].

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import java.util.*;
public class RepeatedDNASequences {
    public static List<String> findRepeatedDnaSequences(String s) {
 
        ArrayList<String> result = new ArrayList<String>();
 
        if(s== null || s.length() == 0) return result;
 
        HashMap<Character,Integer> map = new HashMap<Character,Integer>();
        map.put('A',0);
        map.put('C',1);
        map.put('G',2);
        map.put('T',3);
 
        HashSet<Integer> hashSet = new HashSet<Integer>();
        Set<Integer> unique = new HashSet<Integer>();
 
        int temp = 0;
        for(int i=0;i<s.length();i++){
            /*temp = 0;
              for(int j=0;j<10;j++){
              temp = (temp<<2) + map.get(s.charAt(i+j));
              }*/
            if(i<9){
                temp = (temp<<2) + map.get(s.charAt(i));
                // System.out.println(temp);
            }
            else{
                temp = (temp<<2) + map.get(s.charAt(i));
                temp &amp;= (1<<20) - 1;
                System.out.println(temp);
                if(hashSet.contains(temp) &amp;&amp; !unique.contains(temp)){
                    result.add(s.substring(i-9,i+1));
                    unique.add(temp);
                }
                else {
                    hashSet.add(temp);
                }
            }
        }
 
        return result;
    }
 
    public static void main(String[] args) {
        String s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT";
        System.out.println(findRepeatedDnaSequences(s));
    }
}

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