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In
a typical filesystem, there are files, representing complete units of
data. These files are contained in directories, and these directories,
in turn, may be contained in other directories, and so on. A path is a pointer to a specific file or directory in this stucture. Most Unix-like OSes have a single root
directory, that has all other directories and files directly or
indirectly (via other directories) inside it. Such OSes use the
following structure for file paths:
/<directory-name>/<directory-name>/.../<directory-name>/<file-name>
and, correspondingly, the following structure for directory paths:
/<directory-name>/<directory-name>/.../<directory-name>
For example, "/etc/passwd" (all quotes here and below are for
clarity only) points to a file named "passwd" inside a directory named
"etc" inside the root directory. Other valid file names might be
"/home/user/pictures/me" or just "/file". In this problem, we allow
only nonempty sequences of lowercase letters ('a'-'z') as file and
directory names.
A special case is the root directory itself, which is referred to as just "/".
When a user works with such an OS, one of the directories is chosen
as 'current'. Such a designation allows her to refer to the files in
that directory without specifying the full path to the current
directory. For example, if the current directory is
"/home/user/pictures", then one might refer to the file
"/home/user/pictures/me" as just "me" (note that such a short form can
be easily spotted by the absence of the starting '/' character).
Moreover, the files in subdirectories of the current directory can also
be referred to in a short manner: "/home/user/pictures/others/she" can
be referred to as "others/she".
And even more exciting is the ability to have short references for
files outside the current folder. More specifically, ".." means "the
directory one level above the current directory", "../.." means "the
directory two levels above the current directory", and so on. For
example, if the current directory is "/home/user/pictures", and you
want to refer to "/home/top/data/file", you can express that as
"../../top/data/file".
Given a String path, indicating the complete path to the file that needs to be referred to, and a String currentDir,
indicating the current directory, return a String that contains the
relative path to that file according to the above rules. You should
choose the shortest of all possible relative paths (for example, if the
current directory is "/home/user/pictures", you should use
"../movies/title" and not "../../user/movies/title" as a pointer to
"/home/user/movies/title").
Some files and/or directories may have coinciding names, but it is
impossible to have two files or two directories or a file and a
directory with the same name inside the same directory, so file and
directory paths are not ambiguous. It is guaranteed that the given data
describes a valid file and directory according to the above rules. In
particular, they will not contradict - for example, path="/home/user/some" and currentDir="/home/user/some/other"
are a contradiction, since it implies that a file and a directory both
named "some" exist inside the directory "/home/user".
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