Amazon Interview Experience

Round 1(Online Test):

• Debugging: 7 easy debugging questions
• Question-based on the tree. The difficulty level was medium-hard.
• Question-based on sorting. The difficulty level was easy-medium.
• 45-50 workstyle based assessment
• General Aptitude: 24 questions of varying difficulty levels.

Technical Interview Round 1:

• Zig-zag traversal of a given binary tree. 
• Lowest common ancestor of a given n-ary tree

Technical Interview Round 2:

• Check if a given binary tree is a valid BST. I was asked not to use inorder traversal. So I told him an approach using INT_MIN and INT_MAX which got accepted.
• Given a stream of integers, find the top K most frequent integers.