Count entries in a hash map
Updated
Size is how many keys are stored, not the sum of values and not the last key. Put of a new key +1. Put of an existing key does not change size. Delete of a present key −1.
What to focus on
Size 3 with keys 4,1,9 is three entries even if values are huge. Size is not get(key).
Worked examples
three keys
a = [4, 1, 9] each put once- three distinct keys
Result: size 3
overwrite
a = [4, 1, 9], put 1→99 again- 1 already a key
- size stays 3
Result: size 3
empty
a = []- no keys
Result: size 0
Try it
Write size(m). m is the hash map of key to value. Return how many keys are stored. Overwrite does not change size. Delete of a present key drops size by 1. a = [4, 1, 9] each put once → size 3. a = [4, 1, 9], put 1→99 again → size 3. a = [] → size 0.
keys are integers. Empty is in the cases. Deletes named in the drill are present keys.