137. Single Number II

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.

Example 1:

Input: nums = [2,2,3,2]
Output: 3

Example 2:

Input: nums = [0,1,0,1,0,1,99]
Output: 99

Constraints:

• 1 <= nums.length <= 3 * 104
• -231 <= nums[i] <= 231 - 1
• Each element in nums appears exactly three times except for one element which appears once.

Follow up: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

# @lc code=start
using LeetCode

function single_number(nums::Vector{Int})::Int
    a, b = 0, 0
    for num in nums
        b = (b ⊻ num) & ~a
        a = (a ⊻ num) & ~b
    end
    return b
end
# @lc code=end

single_number (generic function with 1 method)

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