Single Number.md

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?

Example 1:

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

Input: [4,1,2,1,2]
Output: 4

My code:

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        tmp_dict={}
        for num in nums:
            if num not in tmp_dict:
                tmp_dict[num]=1
            else:
                tmp_dict[num]+=1
        for key in tmp_dict.keys():
            if tmp_dict[key]==1:
                return key
        for key in tmp_dict.keys():
            return key

Solution: https://leetcode.com/problems/single-number/