Medium
邏輯簡單沒什么好說的，維持兩個(gè)hashSet, 一個(gè)裝見到過的，一個(gè)裝要求的重復(fù)的软驰。遍歷的時(shí)候涧窒，記得index不要越界，找到那些seen里面見過的加到repeated里锭亏，不然就加到seen里纠吴。最后hashSet轉(zhuǎn)arrayList的方法很方便
List<String> res = new ArrayList<String>(repeated);
class Solution {
public List<String> findRepeatedDnaSequences(String s) {
Set<String> seen = new HashSet<>();
Set<String> repeated = new HashSet<>();
for (int i = 0; i + 9 < s.length(); i++){
String str = s.substring(i, i + 10);
if (!seen.contains(str)){
seen.add(str);
} else {
repeated.add(str);
}
}
List<String> res = new ArrayList<String>(repeated);
return res;
}
}
