@wavy Hi, we do not support sorting by difficulty and problem number.
The question list page has a more predictable sorting behavior.
For example, if you go to: https://leetcode.com/problemset/all/?companySlugs=facebook, then click on "Difficulty" column to sort by difficulty, it will first sort by Difficulty column, then by Acceptance column. This is because Acceptance is kind of related to Difficulty, and if a user wants to sort by easiest questions first, they probably are looking to see it in the order of the highest acceptance rate first.
Not sure if this helps you, please let me know if you think of a better way. Thanks!