Linked Lists: Chains of Data

Dive into linked lists, the dynamic alternative to arrays that excels at insertions and deletions.

What Is a Linked List?

Imagine a scavenger hunt. You get a clue that tells you where the next clue is hidden. You can't just jump to the final prize; you have to follow the chain of clues one by one. A linked list works in a very similar way. It's a sequence of "nodes," where each node contains two pieces of information:

• Data: The actual value being stored (like a number, a string, or an object).
• A Pointer: A reference (or "link") to the very next node in the sequence.

The first node is called the Head, and the last node's pointer is typically `null`, signaling the end of the list. Unlike arrays, nodes in a linked list are not stored in contiguous memory. They can be scattered all over, connected only by the pointers. This structure gives them unique performance characteristics. Access is O(n); insert/delete at a known node is O(1). Reverse, merge two sorted lists, and fast/slow cycle detection are intern-loop staples. Senior rounds rarely start here unless the role is systems-heavy. Fast/slow is the same idea as two pointers.