sadzawka

let sadzawka arr start =
        let n = Array.length arr in
        let d = Array.make_matrix n n 0 in
        let q = Queue.create () in
        Queue.add start q;
        let (x,y) = start in
        d.(x).(y) <- arr.(x).(y);

        let decision (x1,y1) (x2,y2) =
                let m = min d.(x1).(y1) arr.(x2).(y2) in
                if(m > d.(x2).(y2)) then (d.(x2).(y2) <- m; true)
                else false
        in

        while (Queue.is_empty q <> true)
        do
                let (ci,cj) = Queue.take q in
                if ci>0 then
                        if decision (ci,cj) (ci-1,cj) then (Queue.add (ci-1,cj) q;);
                if ci<n-1 then
                        if decision (ci,cj) (ci+1,cj) then (Queue.add (ci+1,cj) q;);
                if cj>0 then
                        if decision (ci,cj) (ci,cj-1) then (Queue.add (ci,cj-1) q;);
                if cj<n-1 then
                        if decision (ci,cj) (ci,cj+1) then (Queue.add (ci,cj+1) q;);
        done;

        let maxi = ref 0 in
        for i = 0 to n-1
        do
                if d.(0).(i) > !maxi then (maxi:=d.(0).(i););
                if d.(i).(0) > !maxi then (maxi:=d.(i).(0););
                if d.(n-1).(i) > !maxi then (maxi:=d.(n-1).(i););
                if d.(i).(n-1) > !maxi then (maxi:=d.(i).(n-1););
        done;
!maxi