%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/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

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

/any { % [a b] proc -> bool
    1 dict begin
    /p exch def
    false exch
    {
        p {
            pop true
            exit
        } if
    } forall
    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

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


% end included library code

/maximalsquare {
    0 dict begin
    /a exch def
    /mx 0 def
    /boundy a length def
    /boundx a 0 get length def
    0 1 boundy 1 sub {
        /y exch def
        0 1 boundx 1 sub {
            /x exch def
            /size 0 def
            {
                [
                    x 1 x size add {
                        [ exch y size add exch ]
                    } for
                    size 0 gt {
                        y 1 y size add {
                            [ exch x size add ]
                        } for
                    } if
                ]
                {
                    /i exch def
                    a i 0 get get i 1 get get
                } map
                { 0 eq } any {
                    exit
                } if
                /size size 1 add def
                x size add boundx ge
                y size add boundy ge or {
                    exit
                } if
            } loop
            /mx mx size dup mul max def
        } for
    } for
    mx
    end
} bind def

(maximalsquare) test.start
[[1 0 1 0 0] [1 0 1 1 1] [1 1 1 1 1] [1 0 0 1 0]] maximalsquare 4 eq test
[[0 1] [1 0]] maximalsquare 1 eq test
[[0]] maximalsquare 0 eq test
test.end