# File warshall.rb, line 21
        def to_s
                return "{}" if @array == nil
                n=0
                str = "{ " + @array[0].to_s
                while n<=@array.length
                        n+=1
                        str += ',' + @array[n].to_s if @array[n]!=nil
                end
                return str + " }"
        end