bfs

let bfs mat start finish=
        let n = Array.length mat in
        let q = Queue.create () in
        let visited = Array.make n 0 in
        Queue.add start q;
        let flague = ref false in
        while (Queue.is_empty q <> true && !flague <> true)
        do
                let cur = Queue.take q in
                for i = 0 to n-1
                do
                        if ((mat.(cur).(i) = 1)&&visited.(i)=0)
                                then
                                (if i = finish then (flague:=true;)
                                else
                                        begin
                                        Queue.add i q;
                                        visited.(i)<-1;
                                        end;)
                done;
        done;
!flague