Do not assume map iteration order
Updated
Hash maps are unordered unless the language documents insertion-order. Algorithm problems must not rely on first key is the smallest after a hash put.
What to focus on
If you need sorted keys, sort them. If you need first-seen order, store a list alongside the map. Tests that pass because the hash was lucky will fail on another runtime.
Worked examples
not sorted
a = [9, 1, 4] as keys- iteration might be 9,1,4 or 1,4,9
Result: do not claim sorted
not array order
a = [4, 1, 9]- buckets scramble
Result: not necessarily 4 then 1 then 9
empty
a = []- no order to assume
Result: {}
Try it
Write keys(m). m is the hash map. Print keys. Do not claim sorted order or array order. Sort explicitly when you need 1, 4, 9. a = [9, 1, 4] as keys → do not claim sorted. a = [4, 1, 9] → not necessarily 4 then 1 then 9. a = [] → {}.
keys are integers. Empty is in the cases.