%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/s2a {
    [ exch { } forall ]
} bind def

/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

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

/dget {
    3 1 roll
    2 copy
    known {
        get exch pop
    } {
        pop pop
    } ifelse
} bind def

/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def

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


/deepcopy {
    2 dict begin
    /a exch def
    a type /dicttype eq {
        <<
            a keys {
                /k exch def
                k
                a k get deepcopy
            } forall
        >>
    } {
        a type /arraytype eq {
            [
                a {
                    deepcopy
                } forall
            ]
        } {
            a type /stringtype eq {
                a dup length string cvs
            } {
                a
            } ifelse
        } ifelse
    } ifelse
    end
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def

/deepeq {
    2 dict begin
    /a exch def
    /b exch def
    a type b type eq {
        a type /dicttype eq {
            a length b length eq {
                <<
                    a {
                        pop
                        true
                    } forall
                    b {
                        pop
                        true
                    } forall
                >>
                true exch
                {
                    pop
                    dup a exch known {
                        dup b exch known {
                            dup a exch get exch b exch get deepeq not {
                                pop false
                            } if
                        } {
                            false
                        } ifelse
                    } {
                        false
                    } ifelse
                } forall
            } {
                false
            } ifelse
        } {
            a type dup /arraytype eq exch /stringtype eq or {
                a length b length eq {
                    true
                    0 1 a length 1 sub {
                        dup a exch get exch b exch get deepeq not {
                            pop false
                            exit
                        } if
                    } for
                } {
                    false
                } ifelse
            } {
                a b eq
            } ifelse
        } ifelse
    } {
        false
    } ifelse
    end
} bind def


% end included library code

/commoncharacters {
    0 dict begin
    /a exch def
    [
        a {
            /h 0 dict def
            s2a {
                /c exch def
                h c 2 copy 0 dget 1 add put
            } forall
            h
        } forall
    ] /ac exch bind def
    /vc ac 0 get deepcopy def
    ac {
        /aa exch def
        vc keys {
            /c exch def
            aa c known {
                vc c 2 copy get aa c get min put
            } {
                vc c undef
            } ifelse
        } forall
    } forall
    [
        a 0 get s2a {
            /c exch def
            vc c known {
                c
                vc c 2 copy get 1 sub put
                vc c get 0 eq {
                    vc c undef
                } if
            } if
        } forall
    ] { 1 string dup 3 2 roll 0 exch put } map
    end
} bind def

(commoncharacters) test.start
[(java) (javascript) (julia)] commoncharacters [(j) (a)] deepeq test
[(bella) (label) (roller)] commoncharacters [(e) (l) (l)] deepeq test
[(cool) (lock) (cook)] commoncharacters [(c) (o)] deepeq test
test.end