268 - Missing Number

Details

Key	Value
Link	https://leetcode.com/problems/missing-number/
Language	Python 3
Runtime	148 ms, faster than 77.91% of Python3 online submissions for Missing Number
Memory Usage	15.5 MB, less than 14.37% of Python3 online submissions for Missing Number
Datastructures	List[int]
Algorithms	iterate, xor, lambda/reduce

Procedure

1. TBD...

Code

Option 1: Iterate & XOR

class Solution:
    def missingNumber(self, nums: List[int]) -> int:
        answer = 0
        for i, num in enumerate(nums):
            answer ^= i + 1
            answer ^= num
        return answer

Option 2: Lambda & Reduce

class Solution:
    def missingNumber(self, nums: List[int]) -> int:
        lambda_xor = lambda x,y: x ^ y
        nums_range = list(range(len(nums)+1))      
        return reduce(lambda_xor, nums_range + nums)

Option 3: One-liner Lambda & Reduce

class Solution:
    def missingNumber(self, nums: List[int]) -> int:
        return reduce(lambda x,y: x ^ y, list(range(len(nums)+1)) + nums)