“No matter how advanced they become, experts never lose sight of the fundamentals. In many ways, they are advanced for that very reason: they understand the fundamentals better than anyone else."
~James Clear

Competitive Programming is a continuous cycle of coding, endless debugging, and facing a few failures till you finally succeed! A few reasons why competitive programming is highly beneficial are:

• It enhances your problem solving and debugging skills
• It helps you write cleaner and optimal code
• It improves your fundamentals
• It helps you showcase your skills
• It prepares you for technical interviews

To brush up my knowledge of data structures and algorithms I decided to take part in the 30 days coding challenge by Leetcode

Problem definition: Single number

Given a non-empty array of integers, every element appears twice except for one. Find that single one.

Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Sample Testcase

Testcase 1

Input: [2,2,1]
Output: 1

Testcase 2

Input: [4,1,2,1,2]
Output: 4

I highly encourage you to attempt this problem on your own before looking at my solution.

Solution

Although the preferred language for Competitive Coding is C/C++ I have used Python for my accepted solution!

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        nums.sort()
        for i in range(0,len(nums),2):
            if(i==len(nums)-1):
                return nums[i]
            elif(nums[i]!=nums[i+1]):
                return nums[i]

Submission Details

Total test cases passed: 16/16
Runtime: 92 ms
Memory Usage: 16.5 MB

Note: This submission was better than 41.59% of Python3 solutions in terms of runtime. Therefore a better approach to reduce the time complexity can be thought of! 🌚

I would really recommend you to explore this side of the Computer Science and tune in to the journey of competitive programming to write better, cleaner, efficient and optimal code! 😀

If you have a better approach to this problem, or for any other queries feel free to reach out to me! 😇