Linked Lists Interview Questions
Linked list questions test pointer discipline: reversal, cycle detection with fast and slow pointers, and merging — all with careful null handling.
Linked list problems test whether you can manipulate pointers without losing the list. They are less about algorithmic insight than about precision: reversing a list, detecting a cycle, finding a midpoint, or merging two sorted lists are all short solutions where a single misordered assignment loses every node after the current one.
What interviewers probe
The two techniques worth having automatic are the fast-and-slow pointer pair, which finds cycles and midpoints in one pass, and the dummy head node, which removes most of the special-casing around modifying the first element. Interviewers watch for whether you draw the pointer reassignments before writing them, because doing it in your head is where the mistakes come from.
Practice linked lists
5 coding · 3/1/1 easy/medium/hard
Linked Lists interview questions — FAQ
What is the fast and slow pointer technique?
Two pointers advancing at different speeds through the list. If they ever meet, there is a cycle; when the fast pointer reaches the end, the slow one is at the midpoint. It solves several classic questions in one pass with constant space.
Why use a dummy head node?
It removes the special case where the operation changes the first element. With a dummy node in front, insertion and deletion at the head look identical to every other position, which cuts the branching a solution needs.