136. Single Number
Given an array of integers, every element appears twice except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
My Solution
class Solution(object):
def singleNumber(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
r = 0
for i in range(len(nums)):
r ^= nums[i]
return r
Reference (转)
def singleNumber1(self, nums):
dic = {}
for num in nums:
dic[num] = dic.get(num, 0)+1
for key, val in dic.items():
if val == 1:
return key
def singleNumber2(self, nums):
return 2*sum(set(nums))-sum(nums)
def singleNumber3(self, nums):
return reduce(lambda x, y: x ^ y, nums)
def singleNumber4(self, nums):
return reduce(operator.xor, nums)
