leetcode229. Majority Element II

题目描述（难度（Medium））：

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space.
Hint:
How many majority elements could it possibly have?

Tags： Array
Similar Problems： (E) Majority Element

分析：采用“投票算法”，找到后记住一定要验证。

代码实现：

class Solution(object):    def majorityElement(self, nums):        """        :type nums: List[int]        :rtype: List[int]        最多只会有2个这样的众数        """        n = len(nums)        if n<=1:            return nums        candidate1, candidate2 = None, None        cnt1, cnt2 = 0, 0        for i in range(n):            if nums[i]==candidate1:                cnt1 += 1            elif nums[i]==candidate2:                cnt2 += 1            elif cnt1==0:                candidate1 = nums[i]                cnt1 = 1            elif cnt2==0:                candidate2 = nums[i]                cnt2 = 1            else:                cnt1 -= 1                cnt2 -= 1        #check        cnt1, cnt2 = 0, 0        for i in range(n):            if nums[i]==candidate1:                cnt1 += 1            elif nums[i]==candidate2:                cnt2 += 1        result = []        if cnt1>n/3:            result.append(candidate1)        if cnt2>n/3:            result.append(candidate2)        return result