[leetcode: Python]169. Majority Element

题目：
Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.

You may assume that the array is non-empty and the majority element always exist in the array.

题意：
给定一个数组，找到它的主元素，即出现次数超过n/2的数。
假定数组非空且数组存在主元素。

方法一：性能66ms

class Solution(object):    def majorityElement(self, nums):        """        :type nums: List[int]        :rtype: int        """        b = {}        for eachnum in nums:            if eachnum not in b:                b[eachnum] = 1            else:                b[eachnum] += 1        for eachnum in b:            if b[eachnum] == max(b.values()):                return eachnum        return 0

方法二：性能49ms

class Solution(object):    def majorityElement(self, nums):        """        :type nums: List[int]        :rtype: int        """        return sorted(nums)[(len(nums))/2]