[LeetCode] Majority Element

问题描述：

  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.

关键点在于多于⌊ n/2 ⌋次。按特征切分成两半，一定有一边是多于一半的。可以用哈希，但直接统计个数两两相消可以就地解决。

class Solution:
    # @param num, a list of integers
    # @return an integer
    def majorityElement(self, num):
        cur = 0
        count = 0
        for i in num:
            if(count == 0):
                cur = i
                count+=1
            else:
                if(cur == i):
                    count+=1
                else:
                    count-=1
        return cur