169. Majority Element

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.

Example 1:

Input: [3,2,3]
Output: 3

Example 2:

Input: [2,2,1,1,1,2,2]
Output: 2

找一个数，出现次数大于数字长度的一半。on做法维护一个majority数和他当前遇到相同数的个数，如果下一个数相同，计数+1，否则计数-1，计数=0的时候换majority，因为要找的数长度一定大于数组的一半，因此最后剩下来的数一定是majority

class Solution(object):
    def majorityElement(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        majority = nums[0]
        count = 1
        for i in range(1, len(nums), 1):
            if nums[i] == majority:
                count += 1
            else:
                count -= 1
            if count == 0:
                majority = nums[i]
                count = 1
        return majority