lintcode_46.主元素

Posted 2020-10-18

给定一个整型数组，找出主元素，它在数组中的出现次数严格大于数组元素个数的二分之一。

 注意事项

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

样例

给出数组[1,1,1,1,2,2,2]，返回 1

思路：

1.计数，找数量最多的元素

2.主元素个数大于数量的二分之一，所以排序后的中间元素一定为主元素

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