# Project : Damm algorithm

matrix = [[0, 3, 1, 7, 5, 9, 8, 6, 4, 2],
               [7, 0, 9, 2, 1, 5, 4, 8, 6, 3],
               [4, 2, 0, 6, 8, 7, 1, 3, 5, 9],
               [1, 7, 5, 0, 9, 8, 3, 4, 2, 6],
               [6, 1, 2, 3, 0, 4, 5, 9, 7, 8],
               [3, 6, 7, 4, 2, 0, 9, 5, 8, 1],
               [5, 8, 6, 9, 7, 2, 0, 1, 3, 4],
               [8, 9, 4, 5, 3, 6, 2, 0, 1, 7],
               [9, 4, 3, 8, 6, 1, 7, 2, 0, 5],
               [2, 5, 8, 1, 4, 3, 6, 7, 9, 0]]

see "5724" + encode(5724 ) + nl
see "5727" + encode(5727 ) + nl
see "112946" + encode(112946) + nl

func encode(n)
       check = 0
       for d in string(n)
           check = matrix[check+1][d-'0'+1]
       next
       if check = 0
          return " is valid"
       else
          return " is invalid"
       ok