임시
public int uniqueLetterString(String S) { int size = 0; List<String> prefix = getPrefix(); for(String word : prefix) { Set<Character> set = new HashSet<>(); for(int i=0;i<word.length;i++) { set.add(word[i]); } size+=set.size(); set = new HashSet(); } } private List<String> getPrefix(String s) { List<String> prefix = new ArrayList(); int j = 1; for(int i = 0;i < s.length(); i++) { while(j!=s.length()-1) { prefix.add(s.subString(i,j)) ++j; } j=i+1; } }