FedEx Express Java Developer Interview Questions and Answers

Design a stack that supports getmin in O(1) time and O(1) space complexities.

• Use two stacks, one for storing the actual values and the other for storing the minimum values.

• When pushing a new value, check if it is smaller than the current minimum value and push it to the minimum stack if it is.

• When popping a value, check if it is the current minimum value and pop it from the minimum stack if it is.

• To get the minimum val...read more

Binary tree traversal is the process of visiting each node in a binary tree exactly once in a specific order.

• There are three main types of binary tree traversal: inorder, preorder, and postorder.

• Inorder traversal visits the left subtree, then the root, then the right subtree.

• Preorder traversal visits the root, then the left subtree, then the right subtree.

• Postorder traversal visits the left subtree, then the right subt...read more

LRU cache is a data structure that stores the most recently used items and discards the least recently used items.

• LRU stands for Least Recently Used

• It has a fixed size and when the cache is full, the least recently used item is removed to make space for a new item

• It uses a combination of a doubly linked list and a hash map to achieve O(1) time complexity for both insertion and deletion

• Example: A web browser cache that ...read more

Diameter of a binary tree is the longest path between any two leaf nodes.

• Calculate the height of left and right subtrees recursively.

• Calculate the diameter recursively using the formula max(left_height + right_height + 1, max(left_diameter, right_diameter)).

• Return the maximum diameter.

To find interchanged terms from an AP series

• Identify the common difference between terms

• Swap the positions of adjacent terms

• Check if the new series is also an AP

• Repeat until no more interchanged terms can be found

Database indexing is a technique to improve the performance of database queries.

• Indexing creates a data structure that allows for faster retrieval of data.

• Indexes are created on one or more columns of a table.

• Queries that use indexed columns can be executed faster.

• Indexes can be clustered or non-clustered.

• Clustered indexes determine the physical order of data in a table.

• Non-clustered indexes create a separate structure...read more