1233. Remove sub-folders from the filesystem

//1233. Remove sub-folders from the filesystem

class Solution {
    public List<String> removeSubfolders(String[] folder) {
        Arrays.sort(folder, Comparator.comparing(s -> s.length()));

        Set<String> seen = new HashSet<>();
        
        outer:
        
        for(String f : folder) {
            for(int i = 2; i < f.length(); ++i) {
                if(f.charAt(i) == '/' && seen.contains(f.substring(0, i))) {
                    continue outer;
                }
            }

            seen.add(f);
        }

        return new ArrayList<>(seen);
    }
}