<filename>268-missing-number/268-missing-number.py
class Solution(object):
    def missingNumber(self, nums):
        n = len(nums)
        return n*(n+1)//2 - sum(nums)
<filename>268-missing-number/268-missing-number.py
class Solution(object):
    def missingNumber(self, nums):
        n = len(nums)
        return n*(n+1)//2 - sum(nums)