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


Runtime: 108 ms, faster than 35.27% of Python3 online submissions for Single Number II.

Memory Usage: 16 MB, less than 41.44% of Python3 online submissions for Single Number II.



```python
class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        #9:25
        theDict = dict()
        for num in nums:
            if num not in theDict:
                theDict[num] = 1
            else:
                theDict[num] += 1
        for i in theDict.keys():
            if theDict[i] == 1:
                return i
        return None
        #9:26
```