题目：

题解：

L = 10
bin = {'A': 0, 'C': 1, 'G': 2, 'T': 3}class Solution:def findRepeatedDnaSequences(self, s: str) -> List[str]:n = len(s)if n <= L:return []ans = []x = 0for ch in s[:L - 1]:x = (x << 2) | bin[ch]cnt = defaultdict(int)for i in range(n - L + 1):x = ((x << 2) | bin[s[i + L - 1]]) & ((1 << (L * 2)) - 1)cnt[x] += 1if cnt[x] == 2:ans.append(s[i : i + L])return ans