Dictionaries and sets

Look values up by key, and keep only unique items.

A dictionary maps keys to values. Lookups are fast however large it gets.

Expected output

Ravi
not given
name = Ravi
dept = CSE
year = 3

Counting with a dictionary

This pattern appears in a lot of coding tests.

Expected output

{'b': 1, 'a': 3, 'n': 2}

A set keeps unique items and has no order, so sort it before printing.

Expected output

[2, 3]
[1, 2, 3, 4]
3