Two Sum

As a self-taught developer, the Two Sum question didn't exactly come easy to me on my learning journey, you can say to this day, I still don't understand the question. But I hope by beginning to write and wrack my brain and throw my thoughts on a blog post with a more methodical approach to break down each question would help me better understand data structures and algorithms.

Lately I have been using neetcode.io and following the Grind 75 questions. To better understand the Leetcode classic, I know I have to take a deep dive into the fundamentals of the question such as arrays, hash maps, time-complexity and space-complexity.

Problem Description

Here is the question snipped from LeetCode, now let's take a look at the different fundamental solutions of the problem in both JavaScript and Python!

JavaScript

Python 🐍

  def twoSum(self, nums: List[int], target: int) -> List[int]:
        for i in range(len(nums)):
            for j in range(i + 1, len(nums)):
                if nums[i] + nums[j] == target:
                    return [i,j]

Here is my first approach, a nested for loop where we look through the array for the first pair of indices of the two numbers that add up to the target value.