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