IBM Software Engineer Interview Questions and Answers

Reversing a linked list involves changing the direction of the pointers between nodes.

• 1. Start with three pointers: previous (null), current (head), and next (null).

• 2. Iterate through the list: set next to current's next, current's next to previous, then move previous and current forward.

• 3. Continue until current is null, then set head to previous.

• Example: For list 1 -> 2 -> 3, after reversal it becomes 3 -&...read more

Implement a stack that supports finding the minimum element in constant time.

• Use two stacks - one to store the actual elements and another to store the minimum values at each level.

• When pushing an element, compare it with the current minimum and push the smaller value onto the minimum stack.

• When popping an element, also pop from the minimum stack if the popped element is the current minimum.

SQL is a relational database management system, while NoSQL is a non-relational database management system.

• SQL databases are table-based and have a predefined schema, while NoSQL databases are document-based, key-value pairs, graph databases, or wide-column stores.

• SQL databases are good for complex queries and transactions, while NoSQL databases are better for hierarchical data storage and real-time web applicatio...read more

Design patterns are reusable solutions to common problems in software design.

• Design patterns provide a way to create flexible and maintainable software systems.

• They help in organizing code, improving code readability, and promoting code reusability.

• Examples of design patterns include Singleton, Factory, Observer, and Strategy patterns.

Merge is used to combine two or more sets of data into a single set.

• Merge is commonly used in version control systems to combine different branches of code.

• It is also used in databases to combine data from multiple tables.

• Merge can be used in sorting algorithms to combine two sorted arrays into a single sorted array.

The lowest common ancestor of two nodes in a tree is the node that is the closest ancestor to both nodes.

• Traverse the tree from the root to find the paths from the root to each node.

• Compare the paths to find the last common node between the two paths.

• The last common node is the lowest common ancestor.