Find the most frequent key
Updated
Scan the map (or track best while building) for the max count. Ties need a rule: first-seen, smallest key, or any.
What to focus on
Do not scan the original array again if you already have the map unless you need first-seen and did not store order.
Worked examples
clear winner
a = [4, 1, 9, 1]- 1 has 2
Result: mode key 1
tie first-seen
a = [2, 3, 2, 3]- 2 and 3 both 2
- 2 appeared first
Result: mode 2 under first-seen
all unique
a = [4, 1, 9]- every count 1
- first-seen 4
Result: mode 4 (tie rule)
Try it
Write modeKey(a). a is an array of integers. Build a frequency map. Return the key with the largest count. Ties use first-seen. a = [4, 1, 9, 1] → mode key 1. a = [2, 3, 2, 3] → mode 2 under first-seen. a = [4, 1, 9] → mode 4 (tie rule).
a is a non-empty list of integers. Ties use first-seen.