题目
All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.
Write a function to find all the 10-letter-long sequences (substrings) that occur more than once in a DNA molecule.
答案
class Solution {
public List<String> findRepeatedDnaSequences(String s) {
if(s.length() < 10) return new ArrayList<String>();
Set<String> set = new HashSet<>();
Set<String> list_set = new HashSet<>();
for(int i = 0; i + 10 <= s.length(); i++) {
String curr = s.substring(i, i + 10);
if(set.contains(curr)) {
list_set.add(curr);
}
else {
set.add(curr);
}
}
return new ArrayList<>(list_set);
}
}
