Amazon SDE3 client-side engineering [reject]

I’m a veteran developer in the problem domain

Phone screen:
Talk about a recent technical challenge (in the last five years)
Find closest common node in a non-binary tree

Onsite: (5 interviews, 1 hour each)
Tech questions
Find an empty cubby in a locker that will fit a package
Interleave a linked list first element, last element, second element, n-1 element, etc in place (without using another data structure)
Architect an app (within the same problem domain as the job)
Report the kth most popular string in an incoming stream of strings; the best answer would have gone all the way to asynchronously updating the priority queue after new strings came in.

‘Leadership principles’ questions:
Talk about a time you were criticized and how you handled it
Talk about a time you went above-and-beyond a problem spec
Talk about a time you had to go down several layers/apis to solve a technical problem
Talk about how you’ve gone about hiring people. Have you ever hired someone smarter than you?
Talk about how you’ve mentored.
Talk about a time you disagreed with a plan of action; this came up a couple of times in different ways, I forget the exact questions.
Talk about a time you simplified something complicated.

I felt like I’d never done so well at an onsite, though I did get blocked on the priority queue question and needed a hint to get the space complexity down from n to k.