Two Sums

The Two Sum question is a leetcode question that works on finding two numbers in an array whose sum equals a given target Let’s understand the question: Given an array nums and a target value, return the indices of the two numbers such that they add up to the target. example target = 9 Output : [2,7] because 2+ 7 -> 9 *Approach * I came to know there are 3 ways to solve this question they were *brute force - > comparing all possible pairs hashing -> store all previous traverse optimized -> by difference * I choose optimized approach it is the most time and memory efficent approach, I started with a question "Do I really need to check all pairs?” That felt slow and so was hashing “Can I remember what I’ve already seen?” step 1: Target - current number and move that value to another list dif = [] loop 1 nums = [2, 7, 11, 15] dif = [] 9 - nums[0] - > 2 2 not in dif so -> dif = [2] loop 2 nums = [2, 7, 11, 15] 9-nums[1] -> 2 2 in dif then that means the pair is found A