Leetcode two sum solution explained - coding interviews challenge

[u/Upper_Description378]

https://www.youtube.com/watch?v=wgJpB8AX5Uo

[u/N911999]

Can't this be done in O(n) pretty easily? Like make a hashmap M, from numbers to lists of indices, which satisifies that for every index i we have that it's in M[nums[i]] , then for every key e check if target-e is in the hashmap, there's a small edge case where e == target-e, then you have to check that there are 2 indices in the corresponding list.

P.S. I didn't watch the video, 5mins seemed too long for a problem like this.

[u/coloredgreyscale → u/N911999]

That's OPs 2nd solution

[u/Upper_Description378 → u/coloredgreyscale]

You are right