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Tested Python solution for LeetCode 137 with 18 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 137 # by problem number
lcpy gen -s single_number_ii # by problem name
nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.
You must implement a solution with a linear runtime complexity and use only constant extra space.
Input: nums = [2,2,3,2]
Output: 3
Input: nums = [0,1,0,1,0,1,99]
Output: 99
class Solution:
# Time: O(n)
# Space: O(1)
def single_number(self, nums: list[int]) -> int:
ones = 0
twos = 0
for num in nums:
ones = (ones ^ num) & ~twos
twos = (twos ^ num) & ~ones
return ones
| Time | Space |
|---|---|
| O(n) | O(1) |