leetcode series - most elements (see the solution to a problem, I was shocked Series)

Category: array

Algorithms: Boyer-Moore algorithm

169. Most of the elements

Given an array of size n, the majority of the elements found therein. Most of the elements in the array refers to the number of occurrences greater than ⌊ n / 2 ⌋ elements.

You can assume that the array is non-empty, and there is always most elements of a given array.

Example 1:

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

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

answer

Maintain a count, most elements encountered +1, or by 1, so the final count must be positive. In iterate the process, after the encounter is cleared, re the current digital value as a candidate, re-counted.

Code

class Solution(object):
    def majorityElement(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        # Boyer-Moore 算法
        candi = nums[0]
        count = 0
        for i in nums:
            if count==0:
                candi=i
            count += (1 if i==candi else -1)
        return candi