python--剑指offer--中等--56 - II. 数组中数字出现的次数 II

from typing import List


class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        ones = twos = 0
        for num in nums:
            ones = ones ^ num & ~ twos
            twos = twos ^ num & ~ ones
        return ones


if __name__ == '__main__':
    solution = Solution()
    nums = [9, 1, 7, 9, 7, 9, 7]
    res = solution.singleNumber(nums)
    print(res)

from typing import List


class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        counts = [0] * 32
        for num in nums:
            for i in range(32):
                counts[i] += num & 1
                num >>= 1

        res, m = 0, 3
        for i in range(31, -1, -1):
            res <<= 1
            # res += counts[i] % m
            res |= counts[i] % m

        return res if counts[31] % m == 0 else ~(res ^ 0xffffffff)


if __name__ == '__main__':
    solution = Solution()
    nums = [9, 1, 7, 9, 7, 9, 7]
    nums = [3, 4, 3, 3]
    res = solution.singleNumber(nums)
    print(res)