Recitation 5

From 6.006 Introduction to Algorithms

Can we hash in constant time?

If your object is of constant size (like a 32-bit integer, or an English word) then you can hash in constant time.

If, however, your object is large (like a large python integer, or a DNA string) then hashing takes time linear in the size of the object.

Python Internal Hash

python hash (reimplemented)

We went over how python hashes:

• ints
• strings
• tuples

Mutability

Python does not allow you to put lists in dictionaries, because they are mutable.

.__hash__()

We gave a simple example of how to implement a hash function in your own class