I took my virtual onsite interview round for internship in Bloomberg London.There were 2 engineers in the meeting.

Question was basically valid parantheses question in leetcode which followed by some follow-ups like "what happens if I want to invent some custom parantheses like "<>"?". I implemented hashmap for different paranthesis types using std::map.

After that other enginner asked me some questions about time complexity of std::map and std::unordered_map in C++.I answered them for std::map as it is a binary search tree basically, but choked on describing how unordered_map has O(1) time complexity.Interviewee wanted me to describe how it is O(1) and what is hashing? but I couldn't properly.I just feel like I will be rejected because of this even though I answered all questions nicely before this :(