# Links

Go to my solution

Go to the question on LeetCode

# My Thoughts

**What Went Well**

I created a solution quickly that was both fast and space efficient.

# Algorithm Description

**Gauss Sum -** Outputs the sum of all numbers from 0 - n \(n(n+1)\over 2\)

# Solution Statistics

**Time Spent Coding**

10 minutes

**Time Complexity**

O(n) - Every element in nums must be iterated over once, resulting in the O(n) time complexity.

**Space Complexity**

O(1) - One variable was created and the number of variables created does not depend on n, resulting in the O(1) space complexity.

**Runtime Beats**

86.63% of other submissions

**Memory Beats**

88.74% of other sumbissions

# Solution

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class Solution(object):
def missingNumber(self, nums):
n = len(nums)
# Gauss Sum - n * (n + 1) / 2)
return int(n * (n + 1) / 2) - sum(nums)