169. Majority Element

问题

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.

python 代码

class Solution:
    # @param num, a list of integers
    # @return an integer
    def majorityElement(self, num):
        if len(num) == 0:
            return

        counter = {}
        for i in num:
            if i in counter.keys():
                counter[i] =counter[i] + 1
            else:
                counter[i] = 1

        majority = counter.keys()[0]

        for (k, v) in counter.items():
            if v > counter[majority]:
                majority = k

        return majority if counter[majority] >= len(num)/2 else None