My first interview at Microsoft was cool but difficult. The interviewer asked me to tell him about a project I completed in university. He also asked basic questions such as "What is polymorphism?" and "What is inheritance?"

Then the interview actually started. He asked me about binary tree serialization, including code writing. He left me alone in the room for a couple of minutes and then reviewed my code with me. He also asked me to sketch on the board what I did.

He then asked me one more question about "SetAll" in O(1). It was an easy (and tricky) question, but I didn't know the solution. He tried to help me, but I failed. After 90 minutes, the interview ended.

Serialization/Deserialization of a Binary Tree

Data structure to set all values in O(1)