Create a hash map
Updated
A hash map stores key → value pairs. Creating one means starting empty: no keys, size 0. You put pairs later. Empty is a real map, not a missing structure.
What to focus on
We write {4:2} for key 4 maps to value 2. Empty is {}. Keys are unique. After creation there is no legal get-without-default until you put something.
Worked examples
empty
a = []- allocate an empty map
- no keys
Result: {} · size 0
one pair
a = [4], value 2- put 4→2
Result: {4:2} · size 1
three pairs
a = [4, 1, 9], values 2, 8, 3- put 4→2, 1→8, 9→3
Result: {4:2, 1:8, 9:3} · size 3
Try it
Write create(). No arguments. Return the map after the listed puts. Do not print. The key names the slot. The value lives in that slot. a = [] → {} · size 0. a = [4], value 2 → {4:2} · size 1. a = [4, 1, 9], values 2, 8, 3 → {4:2, 1:8, 9:3} · size 3.
keys and values are integers. Creating {} is allowed.