Iterate the keys of a map
Updated
keys() yields each stored key once. It does not yield values. The set of keys is the domain of get.
What to focus on
Do not expect sorted keys. Sorting keys is an extra O(k log k) step you opt into.
Worked examples
three
a = [4, 1, 9] as {4:2,1:8,9:3}- three keys
Result: key set {4, 1, 9}
one
a = [7] as {7:3}- one key
Result: {7}
empty
a = []- no keys
Result: {}
Try it
Write keys(m). m is the hash map. Return each stored key once. Do not sort unless asked. Iteration order is unspecified. a = [4, 1, 9] as {4:2,1:8,9:3} → key set {4, 1, 9}. a = [7] as {7:3} → {7}. a = [] → {}.
keys are integers. Empty is in the cases. Iteration order is unspecified.