Concepts3
⚙️AlgorithmIntermediate
Tree DP - Rerooting Technique
Rerooting (a.k.a. 换根 DP) computes a per-node answer as if each node were the root, in total O(n) time on trees.
#rerooting#tree dp#prefix suffix+11
🗂️Data StructureAdvanced
Segment Tree - Handling Multiple Lazy Operations
When a segment tree supports multiple range updates, you must define how lazy tags compose, because the order of operations matters and composition is not commutative.
#segment tree#lazy propagation#range add+12
🗂️Data StructureIntermediate
Segment Tree Basics
A segment tree is a complete binary tree that stores information about array intervals to answer range queries and support point updates in O(log n).
#segment tree#range query#point update+11