Python Data Structures and Algorithms

Perfect hashing functions

A perfect hashing function is one in which each string (as we are limiting the discussion to strings for now) is guaranteed to be unique. In practice, hashing functions normally need to be very fast, so trying to create a function that will give each string a unique hash value is normally not possible. Instead, we live with the fact that we sometimes get collisions (two or more strings having the same hash value), and when that happens, we come up with a strategy for resolving them.

In the meantime, we can at least come up with a way to avoid some of the collisions. We could, for example, add a multiplier, so that the hash value for each character becomes the multiplier value, multiplied by the ordinal value of the ...