F lcs(a, b)
   V lengths = [[0] * (b.len+1)] * (a.len+1)
   L(x) a
      V i = L.index
      L(y) b
         V j = L.index
         I x == y
            lengths[i + 1][j + 1] = lengths[i][j] + 1
         E
            lengths[i + 1][j + 1] = max(lengths[i + 1][j], lengths[i][j + 1])

   V result = ‘’
   V j = b.len
   L(i) 1..a.len
      I lengths[i][j] != lengths[i - 1][j]
         result ‘’= a[i - 1]
   R result

print(lcs(‘1234’, ‘1224533324’))
print(lcs(‘thisisatest’, ‘testing123testing’))