Solution to removing subfolders from folder (https://leetcode.com/problems/remove-sub-folders-from-the-filesystem/submissions/)

Subfolders.java

public static List<String> removeSubfolders(String[] folders) {
    HashSet<String> rootFoldersOnly = new HashSet<>();
    HashSet<String> setFolders = new HashSet<>(Arrays.asList(folders));

    for (String folder: folders) {
        int searchIndex = 0;
        int currentSegmentIndex = 1;
        String matchingDirectory = "";
        String[] segments = folder.split("/");

        while(currentSegmentIndex < segments.length) {
            searchIndex += segments[currentSegmentIndex].length() + 1;
            String segment = folder.substring(0, searchIndex);
            matchingDirectory = segment;

            if (setFolders.contains(matchingDirectory.toString())) {
                rootFoldersOnly.add(segment);
                break;
            }

            currentSegmentIndex++;
        }
    }

    return new ArrayList<>(rootFoldersOnly);
}