LeeC187 Repeated DNA Sequences

class Solution
{
 public:
     vector<string>findRepeatedDnaSequence(string s)
     {
       vector<string> res;
       unordered_map<int,int>m;
       int cur = 0; int mask = 0x7ffffff;
       for (int i = 0; i < 9;++i)
       {
          cur = (cur << 3) | (s[i] & 7);
       }
       for (int i = 9; i < s.size();++i)
       {
          cur = ((cur&mask) << 3) | (s[i] & 7);
          if (m.find(cur) != m.end())
          {
              if (m[cur] == 1) res.push_back(s.substr(i-9,10));
              ++m[cur];
          }
          else{
             m[cur] = 1;
          }
      }
      return res;
  }
}