Linked List
Navigate node-based data structures with pointer manipulation.
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Problems
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Easy
8
Medium
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Hard
How Linked List Works
Linked List problems typically use pointer manipulation techniques. The two most important patterns are the fast/slow pointer (tortoise and hare) for cycle detection and finding midpoints, and dummy head nodes for simplifying insertions/deletions. The fast pointer moves two steps while the slow moves one — when fast reaches the end, slow is at the middle. For cycle detection, if they ever meet, a cycle exists. Reversing a linked list uses three pointers: prev, curr, and next.
When to Use Linked List
Pattern Recognition
Look for these trigger words in problem statements:
reverse linked list
linked-list
merge two sorted lists
linked list cycle
reorder list
remove nth node from end of list
copy list with random pointer
merge k sorted lists
reverse nodes in k-group
Common Mistakes
- Losing reference to nodes by overwriting pointers without saving them first
- Forgetting the edge case of empty lists or single-node lists
- Not using a dummy head node, leading to complex special-case handling for the head
- Infinite loops from incorrect pointer updates during reversal or reordering
When NOT to Use Linked List
- When you need random access by index (use an array)
- When the problem is about subsequences or subarrays (use sliding window or DP)
- When the overhead of pointer manipulation outweighs the benefit
Practice Problems
Master Linked List
Build pattern recognition with interactive MCQs. Understand why to use Linked List, not just how.
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