給定一個整型數組，找出主元素，它在數組中的出現次數嚴格大於數組元素個數的二分之一。

註意事項

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

樣例

給出數組[1,1,1,1,2,2,2]，返回 1

思路：

1.計數，找數量最多的元素

2.主元素個數大於數量的二分之一，所以排序後的中間元素一定為主元素

class Solution:
    """
    @param: nums: a list of integers
    @return: find a  majority number
    
 
"""
    def majorityNumber(self, nums):
        # write your code here
        nums.sort()
        return nums[len(nums)/2]

九章：

class Solution:

    def majorityNumber(self, nums):
        candidate = None
        count = 0
        for num in nums:
            if count == 0:
                candidate 
 
= num
                count += 1
            elif candidate == num:
                count += 1
            else:
                count -= 1
        return candidate

lintcode_46.主元素