repeatedDNASequences via. CodeFights

repeatedDNASequences

All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T. In research, it can be useful to identify repeated sequences within DNA.

Write a function to find all the 10-letter sequences (substrings) that occur more than once in a DNA molecule s, and return them in lexicographical order. These sequences can overlap.

Example

For s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT", the output should be
repeatedDNASequences(s) = ["AAAAACCCCC", "CCCCCAAAAA"].

Input/Output

[time limit] 4000ms (js)
[input] string s

Guaranteed constraints:
0 ≤ s.length ≤ 5000.

[output] array.string

An array containing all of the potential 10-letter sequences that occur more than once in s.

function repeatedDNASequences(s) {
    // All 10 letter sequences
    var myHash = {}
    var repeatedSequences = []
    
    for (var i = 0; i < (s.length - 9); i ++) {
        var thisSubString = s.slice(i, i + 10)
        
        if (!myHash.hasOwnProperty(thisSubString)) {
            myHash[thisSubString] = 1
        } else if (!repeatedSequences.includes(thisSubString)) {
            // Didn't actually need this line below
            // myHash[thisSubString]++
            repeatedSequences.push(thisSubString)
        }
    }

    console.log(repeatedSequences)
    return repeatedSequences.sort()
}