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The strategic guide to node-based algorithms
Section 1 of 3
The art of pointer manipulation. Master the Classic Patterns used by senior engineers to solve node-based challenges with optimal space complexity.
Core patterns that solve 90% of list problems.
Solving distance and cycles
"Utilize two pointers moving at different speeds (1x and 2x) or maintaining a fixed offset gap."
Handling boundaries elegantly
"Create a temporary 'pre-head' node. It prevents NULL pointer exceptions and simplifies head mutations."
Divide and conquer nodes
"Assume the tail sub-problem is already solved, then perform a single pointer swap for the head."
Standard interview questions with detailed teardowns.
"The "Tortoise and Hare" algorithm. Detecting loops in $O(n)$ time and $O(1)$ space."
"If slow and fast meet, there is a cycle. To find the entrance, move slow to head and move both at 1x speed."
"In-place reversal. Reorienting node pointers without allocating extra memory structures."
"The 'Next' pointer is the only thing that changes. Keep a reference to 'prev' and 'next_node' to avoid losing the chain."
"Interleaving two sorted lists into a single consolidated output chain."
"A 'Dummy' head node removes the edge case of an empty initial list, saving you 4-5 'if' statements."
Refine your pointer reflexes with these curated problems.