Sentinel node: a special placeholder node in a doubly linked list.
Simplifies implementation and reduces edge cases.
Typically used at the beginning and/or end of the list.
Provides a uniform approach for handling insertions and deletions.
Eliminates the need for separate head and tail pointers.
Ensures every node has a next and previous pointer, no need to check for null pointers.
Makes the code for managing the doubly linked list cleaner and more efficient.
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