%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/toset { % array -> dict of (value, true)
    << exch
       {
           true
       } forall
    >>
} 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

/apop.left { % [a b c] -> [b c] a
    dup 0 get exch
    [ exch aload length -1 roll pop ] exch
} 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

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

/apush.right { % [a b] c -> [a b c]
    exch
    [ exch aload length 2 add -1 roll ]
} 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

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


% end included library code

/shortestroute {
    14 dict begin
    /destination exch def
    /origin exch def
    /r 0 dict def
    {
        /rt exch def
        0 1 rt length 2 sub {
            /i exch def
            /ri rt i get def
            /j i 1 add def
            /rj rt j get def
            r ri known not {
                r ri 1 dict put
            } if
            r ri get rj true put
            r rj known not {
                r rj 1 dict put
            } if
            r rj get ri true put
        } for
    } forall
    /out 0 array def
    /stack [ [ origin ] ] def
    {
        stack length 0 eq {
            exit
        } if
        /stack stack apop.left /s exch def def
        /l s s length 1 sub get def
        l destination eq {
            /out s def
            exit
        } {
            /s1 s toset def
            r l get keys {
                /pd exch def
                s1 pd known not {
                    /q s aload length array astore def
                    /q q pd apush.right def
                    /stack stack q apush.right def
                } if
            } forall
        } ifelse
    } loop
    out
    end
} bind def

(shortestroute) test.start
[[1 2 6] [5 6 7]] 1 7 shortestroute [1 2 6 7] deepeq test
[[1 2 3] [4 5 6]] 2 5 shortestroute [] deepeq test
[[1 2 3] [4 5 6] [3 8 9] [7 8]] 1 7 shortestroute [1 2 3 8 7] deepeq test
test.end