Use a hash map to map each original node to its copy, then set next and random pointers for the copies. Alternatively, interleave copies with originals to achieve O(1) space, then separate the lists. Discuss trade-offs between time and space complexity.
Pro tip: Clarify whether the original list can be modified; if not, the hash map approach is safer. Also, mention that the interleaving method is more complex but demonstrates deeper understanding.
Restate the problem to ensure clarity: deep copy a linked list with next and random pointers, preserving all relationships.
Decide between hash map (O(n) space) and interleaving (O(1) space). Explain the trade-offs.
Walk through the steps: for hash map, create copies and map; for interleaving, insert copies, set randoms, and split.
State time and space complexity for both approaches and justify.
Consider empty list, single node, random pointing to self or null, and ensure no cycles in the copy.
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