Function hash(int key, int range)
   h = key % range
   if h < 0: h += range
   return h
End Function


//very, very bad
Function hash(string key, int range)
  return 0
End Function

//very bad
Function hash(string key, int range)
  return length(key)
End Function

//not great
Function hash(string key, int range)
  h = 0
  for each char c in the key:
    h += ASCII(c)
  return h % range
End Function

//good
Function hash(string key, int range)
  h = 0
  for each char c in the key:
    h *= 31
    h += ASCII(c)
  return h % range
End Function