%!PS

% begin included library code
% see https://github.com/Firedrake/postscript-libraries/
/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.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

/reduce { % array proc -> value
    2 dict begin
    /p exch def
    /a exch def
    a 0 get
    1 1 a length 1 sub {
        a exch get
        p
    } for
    end
} bind def

/all { % [a b] proc -> bool
    1 dict begin
    /p exch def
    true exch
    {
        p not {
            pop false
            exit
        } if
    } forall
    end
} bind def

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


% end included library code

/equaldistribution {
    8 dict begin
    /list exch def
    /s list { add } reduce def
    s list length mod 0 eq {
        /m s list length idiv def
        /out 0 def
        /w [ list aload pop ] def
        {
            0 1 w length 2 sub {
                /i exch def
                w i get m gt {
                    /v w i get m sub def
                    w i 1 add w i 1 add get m add put
                    /out out v add def
                    w i m put
                } if
                w i get m lt {
                    /v m w i get sub w i 1 add get min def
                    w i 1 add w i 1 add get v sub put
                    /out out v add def
                    w i w i get v add put
                } if
            } for
            w { m eq } all {
                exit
            } if
        } loop
        out
    } {
        -1
    } ifelse
    end
} bind def

(equaldistribution) test.start
[ 1 0 5 ] equaldistribution 4 eq test
[ 0 2 0 ] equaldistribution -1 eq test
[ 0 3 0 ] equaldistribution 2 eq test
test.end