I applied through college or university.

• The first question was about the difference between a complete vs full binary tree.
• The second was to find a node if it is present in a given binary tree using a not recursive solution, with a hint to convert the numbers in binary and try.
• The third covered the complexity of the height of a tree, number of nodes, and etc.

It was a difficult question to optimize the complexity. Please do study about trees and graph data structures perfectly, and be confident in what you are saying. Don't fumble.