Find a file in the given directory Complexity = O(n!)

gistfile1.java

public static File findFile(File file, String fileName){
    File[] files = file.listFiles();
    if (files == null) return null;
    for (File f : files){
        if (f.isFile() && f.getName().equals(fileName)){
            return f;
        } else if (f.isDirectory()){
            return findFile(f, fileName);
        }
    }
      
    return null;
      
}