Linked Lists: Interview Problems & Solutions

Linked List Interview Problems and Solutions

Linked list problems test pointer manipulation, edge case handling, and in-place algorithms. They appear in approximately 15% of coding interviews and are particularly common at Amazon and Microsoft.

The three techniques that solve 80% of linked list problems: fast/slow pointer (Floyd's cycle detection), dummy head node, and reverse-in-place.

Essential Linked List Patterns

• Fast/Slow Pointers — Detect cycles, find middle node, find nth-from-end. Fast moves 2x, slow moves 1x
• Dummy Head — Simplifies edge cases for insertion/deletion at the head. Create a dummy node pointing to head
• Reverse In-Place — Three pointers: prev, current, next. Iterate and reverse links. O(n) time, O(1) space
• Merge Two Sorted Lists — Use dummy head + comparison. Foundation for merge sort on linked lists

Top 5 Linked List Interview Questions

1. Reverse a linked list (iterative and recursive)
2. Detect cycle in a linked list (Floyd's algorithm)
3. Merge two sorted linked lists
4. Remove nth node from end of list
5. Find intersection point of two linked lists

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