Missing Number
Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.
For example,
Given nums = [0, 1, 3] return 2.
Note: Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?
Solution
class Solution(object):
def missingNumber(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
n = len(nums) + 1
sum_n = n * (n-1) / 2
return sum_n - sum(nums)