leetcode 187. 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.

For example,

Given s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT",

Return:
["AAAAACCCCC", "CCCCCAAAAA"].

这题很直白，直接计数感觉太简单，会超时，于是想了种复杂的方法，提交，失望，超时。索性就试试最直接的方法，就是下面这个

class Solution {
public:
vector<string> findRepeatedDnaSequences(string s) {
vector<string>re;
if (s.size()<11)
return re;
map<string, int>count;
for (int i = 0; i <= s.length() - 10; i++)
{
string str = string(s.begin() + i, s.begin() + i + 10);
count[str]++;
}
for (map<string, int>::iterator it = count.begin(); it != count.end(); it++)
if (it->second > 1)
re.push_back(it->first);
return re;
}
};

靠，竟然通过了。。。彻底无语了