【Leetcode 136】 只出现一次的数字

class Solution(object):
def singleNumber(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
no_duplicate_list = []
for i in nums:
if i not in no_duplicate_list:
no_duplicate_list.append(i)
else:
no_duplicate_list.remove(i)
return no_duplicate_list.pop()

class Solution(object):
def singleNumber(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
hash_table = {}
for i in nums:
try:
hash_table.pop(i)
except:
hash_table[i] = 1
return hash_table.popitem()[0]

class Solution(object):
def singleNumber(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
a = 0
for i in nums:
a ^= i
return a

参考链接
​​​ https://leetcode-cn.com/problems/single-number/solution/zhi-chu-xian-yi-ci-de-shu-zi-by-leetcode/​​