%! PS

/quicksort { % [ a c b ] -> [ a b c ]
    1 dict begin
    /arr exch def
    0 arr length 1 sub quicksort.main
    arr
    end
} bind def

/quicksort.main { % lo hi -> (null)
    3 dict begin
    /hi exch def
    /lo exch def
    /xit false def
    lo 0 lt {
        /xit true def
    } if
    hi 0 lt {
        /xit true def
    } if
    lo hi ge {
        /xit true def
    } if
    xit not {
        /p quicksort.partition def
        lo p quicksort.main
        p 1 add hi quicksort.main
    } if
    end
} bind def

/quicksort.partition {
    3 dict begin
    /pivot arr hi lo add 2 idiv get def
    /i lo 1 sub def
    /j hi 1 add def
    {
        {
            /i i 1 add def
            arr i get pivot ge {
                exit
            } if
        } loop
        {
            /j j 1 sub def
            arr j get pivot le {
                exit
            } if
        } loop
        i j ge {
            j
            exit
        } if
        i j quicksort.swap
    } loop
    end
} bind def

/quicksort.swap {
    2 dict begin
    /bi exch def
    /ai exch def
    arr ai get
    arr bi get
    arr exch ai exch put
    arr exch bi exch put
    end
} bind def

/strconcat % (a) (b) -> (ab)  
{ exch dup length
  2 index length add string
  dup dup 4 2 roll copy length
  4 -1 roll putinterval
} bind def

/strjoin % [(a) (b) (c)] (j) -> (ajbjc)
{
    3 dict begin
    /j exch def
    dup 0 get /out exch def
    /first true def
    {
        first {
            pop
            /first false def
        } {
            out j strconcat
            exch strconcat
            /out exch def
        } ifelse
    } forall
    out
    end
} bind def

/toset { % array -> dict of (array, true)
    << exch
       {
           true
       } forall
    >>
} bind def

/keys { % dict -> array of dict keys
    [ exch
      {
          pop
      } forall
    ]
} bind def

/map { % array proc -> array
    2 dict begin
    /p exch def
    [ exch
      {
          p
      } forall
    ]
} bind def

/kdd {
    2 dict begin
    /dirlist exch quicksort def
    /fx dirlist length dict def
    dirlist {
        /d exch def
        [
            d (/*/) strconcat
            {
                dup length d length 1 add dup 3 1 roll sub 2 -1 roll exch getinterval
                dup length string cvs
            } 50 string filenameforall
        ] {
            /f exch def
            fx f known not {
                fx f dirlist length dict put
            } if
            fx f get d true put
        } forall
    } forall
    /mm dirlist length def
    [
        dirlist
         fx keys { dup length string cvs } map quicksort {
            /f exch def
            fx f get length mm ne {
                [
                    dirlist {
                        fx f get exch
                        known {
                            f
                        } {
                            ()
                        } ifelse
                    } forall
                ]
            } if
        } forall
    ]
    end
} bind def

/spaces {
    2 dict begin
    /space ( ) 0 get def
    dup /st exch string def
    0 exch 1 exch 1 sub {
        st exch space put
    } for
    st
    end
} bind def

/tabular {
    1 dict begin
    /d exch def
    /columnlength [
        d 0 get {
            pop 0
        } forall
    ] def
    d {
        /row exch def
        0 1 row length 1 sub {
            /i exch def
            columnlength i columnlength i get row i get length max put
        } for
    } forall
    d {
        /row exch def
        0 1 row length 1 sub {
            /i exch def
            i 0 gt {
                ( | ) print
            } if
            columnlength i get spaces dup 0 row i get putinterval print
        } for
        (\n) print
    } forall
    end
} bind def

[ (dir_a) (dir_b) (dir_c) ] kdd tabular