First unique scan
A returns desk scans package IDs as they arrive; an ID showing up more than once means a duplicate label. Given the scan log in order, return the first ID that appears exactly once in the whole log, or -1 if every ID repeats (or the log is empty). Example: [2, 3, 2, 4, 3] returns 4.
Implement
first_unique_scan(ids: list[int]) → intExamples
in
[[2,3,2,4,3]]out4What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 12 min
solution.py
InputExpectedGot
[[2,3,2,4,3]]4not run yetsample