class Solution {
public:
vector[HTML_REMOVED] findRepeatedDnaSequences(string s) {
vector[HTML_REMOVED] res;
unordered_map[HTML_REMOVED] hash;
if(s.size() < 10) return {};
for(int i = 0;i <= s.size() - 10;i )//注意这里的边界条件
{
string str = s.substr(i,10);
if(hash[str] == 1) res.push_back(str);
hash[str] ;
}
return res;
}
};