Recruiter contacted through a job portal and scheduled 1st interview on just 12 hours prior notice mentioning they have some ongoing drive and there are in a hurry. No mention of the hiring process or interview structure. Just a 1 min call.

Round1:
20-25 mins on current project architecture
https://leetcode.com/problems/copy-list-with-random-pointer/
Cleared round 1

Round 2:
30 mins on current project architecture. Java & Springboot questions
Given a list of kingdoms on a linear line with start point and end point i.e. [(4,8), (8,9),(12,15),(2,5)]. Find the minimum number of bombs required to blow off all the kingdoms. The overlapping kingdoms need only 1 bomb i.e. in given example it will need 2 bombs because the merged kingdoms will look like [(2,9) (12,15)].
At first glance, i thought it to be similar to https://leetcode.com/problems/merge-intervals/ . I explained the approach to the interviewer, but he said O(nlgn) is the brute force and he strictly needs O(n) time complexity. I could not figure out the better solution. He did not allow me to write code as he was not convinced with O(nlgn) solution. At one point he said O(nlgn) is fine but O(nlgn) + O(n) is not allowed, i told him that the order will still be O(nlgn) but he said no its still more than O(nlgn). This was strange for me because i look only for the order of the complexity.

At the end he gave me 10 more mins and asked another question:
Given two arrays of 0-9 integers
[6,8,0,0,5,6,7,6,7,4,3,6,9,9]
[5,9,6,7,4,3,5,6,8,3,5,6,7,6]

Find which one of the two arrays will make the largest number if the digits are rearranged (Sorting is not allowed as he was looking for O(n) solution. I wasn't able to figure out the approach in 10 mins and the interview ended. However, I was able to figure out the solution later.

If Anyone knows the O(n) solution for the kingdom question, please post it in comments.

My experience with Walmart recruitment team was not good. Recruiters were highly unprofessional, may be because they have outsourced it to vendors. They schedule interviews at the time of their own convenience without checking with candidates. I have not received any feedback/email from the recruiter after the last interview and I am hoping the reason be the rejection.