Caching is critical in systems design, from web browsers to database engines. An LRU (Least Recently Used) cache evicts the least recently used entry when full, ensuring hot data stays accessible. Implementing one in code tests your mastery of linked lists, hash maps, and constant-time operations.

Flattening a multilevel doubly linked list pops up in real‑world scenarios like expanding nested comment threads or unfolding embedded...

Finding the intersection node of two linked lists is like spotting the shared checkpoint in two runners’ paths—useful for debugging...

Adding two numbers digit by digit in reverse order is a great warm‑up for handling arbitrary‑precision arithmetic in systems that store...

Checking whether a linked list reads the same forwards and backwards is a great warm‑up that mirrors real‑world tasks like validating...

Removing the Nth node from the end of a linked list is a perfect warm-up for real-world tasks like trimming logs, pruning history...

Finding not just whether a linked list has a cycle but exactly where that cycle begins is a real-world need whenever you’re dealing with...

Detecting a cycle in a linked list is a classic problem that comes up when you need to guard against infinite loops—whether you’re...

Merging two sorted linked lists is like merging two sorted streams of data—think combining two user event logs in chronological order....

Reversing a linked list is one of those fundamental operations that underpins many real-world tasks—reordering a playlist, undo history,...