169. Majority Element
https://leetcode.com/problems/majority-element/description/
又到了一年一度的Majority Number选举，每个数字都为自己投票，Majority Number获得的票数最多。不同的数字会抵消Majority Number的投票。
代码如下：
class Solution:
def majorityElement(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
result = nums[0]
count = 1
for num in nums[1:]:
if num == result:
count += 1
elif count == 0:
result = num
count = 1
else:
count -= 1
return result
229. Majority Element II
https://leetcode.com/problems/majority-element-ii/description/
使用2个候选变量储存结果即可。注意，第一遍的count1和count2并不是2个候选数字在数组中出现的次数，需要重新扫描一遍数组，找出最终结果。
代码如下：
class Solution:
def majorityElement(self, nums):
"""
:type nums: List[int]
:rtype: List[int]
"""
if not nums:
return []
result = []
value1, value2, count1, count2 = nums[0], 0, 1, 0
for i in range(1, len(nums)):
if nums[i] == value1:
count1 += 1
elif nums[i] == value2:
count2 += 1
elif count1 == 0:
value1, count1 = nums[i], 1
elif count2 == 0:
value2, count2 = nums[i], 1
else:
count1 -= 1
count2 -= 1
return list(set([num for num in (value1, value2) if nums.count(num) > len(nums) // 3]))
