A Splay Tree is a self-adjusting binary search tree that reshapes itself based on how it’s used. Instead of trying to stay balanced all the time, it aggressively moves recently accessed nodes closer to the root. The idea is simple: if you touched it, you’ll probably touch it again. Over time, the tree adapts to access patterns rather than an abstract notion of balance. While AVL Trees follow strict rules to stay perfectly balanced, Splay Trees focus on being fast over time.
When you search, insert, or delete a node, the tree performs a series of rotations called "splaying" to bring that node to the root. There are three types of rotations depending on the node’s position: Zig (single rotation), Zig-Zig (double rotation in same direction), and Zig-Zag (double rotation in opposite directions). After splaying, frequently accessed nodes stay near the root, making repeated operations faster.
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Splaying moves an accessed node to the root of the tree through a series of rotations, keeping frequently accessed elements near the root. While a single operation can take O(n), amortized cost over a sequence of M operations is guaranteed to be O(M log n).
Splay Trees do not store any extra balance information (like height in AVL or color bits in Red-Black). This saves node memory footprint while maintaining self-balancing properties.
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