Repeated DNA Sequences

Repeated DNA Sequences

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.

Example

Input: s = “AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT”
Output: [“AAAAACCCCC”, “CCCCCAAAAA”]

Solution

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class Solution:
    def findRepeatedDnaSequences(self, s: str) -> List[str]:
        lenth = len(s)
        if lenth<10:
            return []
        seen = set()
        repeat = set()
        for i in range(lenth-9):
            temp = s[i:i+10:]
            if temp in seen:
                repeat.add(temp)
            else:
                seen.add(temp)
        return list(repeat)