136 Single number

Original Description: Given a non-empty array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

  • 要求: 给一个数组,其中的元素只有一个出现一次,其余均出现两次,找出光棍。

  • 返回: 光棍元素

  • 例子:
    • input: [2,2,1]
    • output: 1


光棍的值 = set内元素之和x2 - 数组元素之和

class Solution(object):
    def singleNumber(self, nums):
        :type nums: List[int]
        :rtype: int
        return sum(set(nums))*2-sum(nums)
        # or can use dict to save count