187. Repeated DNA Sequences

题目来自leetcode

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"].

题目的意思就是如何在一个字符串中找到出现不只一次且长度大于10的字串,python的代码，超简单- -

class Solution:
    # @param s, a string
    # @return a list of strings
    def findRepeatedDnaSequences(self, s):
        rs = []
        keep = set()
        for i in range(len(s)):
            temp = s[i + 0:i + 10]
            if temp in keep:
                if temp not in rs:
                    rs.append(temp)
            else:
                keep.add(temp)

        return rs

主要应用了堆查找速度为1的特性- -