Solving LeetCode 136 in JavaScript (Single Number)

In this video I solve LeetCode problem 136 (Single Number) with the JavaScript programming language. This question has previously appeared during Amazon coding interviews.
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I start by helping you understand what the problem is asking for, then I will go over the pseudo-code/logic for a solution, and finally I will write the solution code explaining each line, step-by-step.
Using my simple and easy-to-understand methodology, I make difficult and complex interview questions incredibly easy to understand. So easy in fact, that even your grandma could do it! 👵🏻
I will be solving a new problem EVERY WEEK, so be sure to smash that subscribe button and hit the notification bell so you don't miss a single one! 😀
▶ Single Number: leetcode.com/problems/single-...
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#programming #codinginterview #leetcode

[@somebody-17546]

You must implement a solution with a linear runtime complexity and use only constant extra space.

[@BabeCrs]

it asks it to be in O(1) space complexity. How would you adapt this for that

[@suvajitchakrabarty]

If in case anyone is interested, the O(1) space complexity requires some bit manipulation. Essentially if you XOR a number with itself, it returns zero, and if you XOR a number with zero, it returns the number itself.
So if you had the following numbers in the list - 3, 3, 2, the XOR between 3 and 3 would return 0, and then XORing 0 with 2 would return 2. Hence if you did a XOR for all numbers in a list which contains 2 of each numbers except for the one number, then you'd get back the number which occurs once.
The code is pretty straightforward since you only need to do a XOR for every number, and return the result.
Code in Javascript -
var singleNumber = function(nums) {
let res = nums[0];
for (let i = 1; i

[@Maybehassanawad]

very useful ❤️

[@feng282]

isn't const ht an Object? When should we use map or object?

[@Moe1993x]

a hash map is simply an object in JS

[@feng282]

@@Moe1993x so when you are asked to build a custom hashmap, should we do const hash = new Map; or const hash = {}?

[@jinbo369]

ht[num] = ht[num] +1 || 1 can you please explain more on this part?

[@m_blaze4508]

the first time, ht[num] will be undefined. At that time, undefined + 1 will be NaN which is false. Hence ht[num] will be initialized 1 because of || 1. It is explained properly at 2:05

[@pineappleapplepens]

developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_OR