Here is my experience interviewing with Facebook.
Main studying method was to do the top 200 problems from the Facebook tagged lits for the past 6 months.
8 YOE - Backend Software Engineer
Phone Screen:
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree-iii/
https://leetcode.com/problems/kth-largest-element-in-an-array/
(but this was for a stream of characters)
Onsite:
Coding Round
https://leetcode.com/problems/product-of-array-except-self/
https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/ (worded as 'find local minimum')
System Design:
Design something similar to Instagram (not with all features)
Users should be able to adds friends, follow friends, and comment on their photos.
Coding Round
https://leetcode.com/problems/sliding-window-maximum/
https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/
Behavioral:
Questions about projects took a lead on, how you handled difficult situation etc.
Follow Up Phone Screen:
https://leetcode.com/problems/first-bad-version/
https://leetcode.com/problems/meeting-rooms-ii/