Yesterday, I had my interview for the SDE position at Josh Technology Group (JTG). The first round was a technical interview where I was asked two main questions:

1st Question:
Remove Nth Node from the End of a Linked List (Leetcode 19)
The requirement was to solve it in O(1) space and with a single traversal. I managed to complete the solution within 20 minutes, and it was working perfectly.

2nd Question:
Convert a Binary Search Tree to a Greater Sum Tree (Leetcode 1038)
This also needed to be solved in O(1) space and with a single traversal. I implemented the solution successfully using an extra variable passed by reference. Although the code was correct and efficient, the interviewer rejected my approach solely because I used a reference variable, stating that it didn't meet the constraints.

After the interview, I spoke with a few other candidates. Interestingly, one of them solved the same problem using a similar approach—also with a reference variable—and their interviewer accepted it. That candidate progressed to the next round, whereas I was rejected.

This experience left me wondering: Are interviews really about skill, or is there an element of luck involved? If luck plays such a significant role, why do people always emphasize that interviews are purely skill-based?