leetcode 187 Repeated DNA Sequences

1.

class Solution {
public:
    vector<string> findRepeatedDnaSequences(string s) {
        vector<string> re;
        unordered_map<string,int> m;
        if(s.empty()||s.size()<10) return vector<string>{};
        for(string::size_type i=0;i<s.size()-9;++i) {
            string str=s.substr(i,10);
            ++m[str];
            if(m[str]==2) re.push_back(str);
        }
        return re;
    }
};

2. 参考：https://www.cnblogs.com/grandyang/p/4284205.html