from typing import List
# 排序后做,题意说最多出现2次。前后做比对,相同则做异或操作即可
class Solution:
def duplicateNumbersXOR(self, nums: List[int]) -> int:
result = 0
nums.sort()
for i in range(len(nums) - 1):
if nums[i] == nums[i + 1]:
result ^= nums[i]
return result