[Leetcode][python3]Day01.Single Number (30-Day LeetCoding Challenge)

30 days! Lets go Lets go!
N2I -2020.04.01

1. My Solution

class Solution:
    def singleNumber(self, nums) -> int:
        dic={}
        for i in nums:
            if i in dic:
                del dic[i]
            else:
                dic[i]=1
        for res,tmp in dic.items():
            return res

2. A better Solution

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        
        count = 0
        for num in nums:
            count ^= num
            
        print(count)
        return count

Explanation:

This solution using XOR to solve the problem. It is the best way which is fast and using only one extra memory.