187. Repeated DNA Sequences

    /*
     * 187. Repeated DNA Sequences
     * 2016-6-4 by Mingyang
     * 简单的hashmap，注意修改一个hashmap的方法，直接map.put(temp,false)就好了
     */
     public static List<String> findRepeatedDnaSequences(String s) {
            List<String> res=new ArrayList<String>();
            int len=s.length();
            if(len<10)
              return res;
            HashMap<String,Boolean> map=new HashMap<String,Boolean>();
            int start=0;
            for(int i=10;i<=len;i++){
                String temp=s.substring(start,i);
                if(map.containsKey(temp)&&(map.get(temp)==true)){
                    res.add(temp);
                    map.put(temp,false);
                }else if(!map.containsKey(temp)){
                    map.put(temp,true);
                }
               start++;
            }
            return res;
        }