Code RoomSingle number appearing once
HardPrep Room Coding #744

Single number appearing once

CodingAlgorithms & data structuresSenior–Staff~25 min

Every element in the integer array nums appears exactly three times except for one element which appears exactly once. Return that single element. Inputs are non-negative integers. Solve it with O(n) time and O(1) extra space (do not use a hash map or sort).

Implement
single_number_iii(nums: list[int]) → int
Examples
in[[2,2,3,2]]out3
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
InputExpectedGot
[[2,2,3,2]]3not run yetsample