Values appearing exactly twice
Given an array a of length n where every value is in the range [1, n], some values appear once and some appear exactly twice. Return a sorted list of all values that appear twice. Aim for O(n) time and O(1) extra space (not counting the output).
Implement
find_duplicates(a: list[int]) → list[int]Examples
in
[[4,3,2,7,8,2,3,1]]out[2,3]What 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 25 min
solution.py
InputExpectedGot
[[4,3,2,7,8,2,3,1]][2,3]not run yetsample