leetcode 日经贴，python code -repeated-dna-sequences

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

class Solution:
    # @param s, a string
    # @return a list of strings
    def findRepeatedDnaSequences(self, s):
        map2Int = {'A':0, 'C':1, 'G':2, 'T':3}
        lst = []
        hah = {}
        if len(s) <= 10: return lst
        current = 0
        for i in range(10):
            current = current * 4 + map2Int[s[i]]
        hah[current] = False
        base = 4 ** 9
        for i in range(10, len(s)):
            current = (current - map2Int[s[i - 10]] * base) * 4 + map2Int[s[i]]
            if current not in hah:
                hah[current] = False
            elif hah[current] == False:
                hah[current] = True
                lst.append(s[i - 9 : i + 1])
        return lst