Order Statistics Tree¶

GNU PBDS ordered tree for online rank, k-th, and count-smaller queries, with a pair-key wrapper when duplicates matter.

Microtopics¶

Source	Type
GCC tree_order_statistics_node_update	`Primary`
GCC PBDS manual	`Primary`
Competitive Programmer's Handbook	`Reference`

Material	Type
Order Statistics Tree hot sheet	`quick reference`
PBDS starter route	`starter route`
ORDERSET note	`anchor note`
Heaps And Ordered Sets tutorial	`compare point`
Fenwick Tree tutorial	`compare point`

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
ORDERSET - Order Statistic Set	`SPOJ`	`Medium`	Order Statistics	Data-Structure-Heavy; Classic	Ordered Set Invariant; Order Of Key; Find By Order	Kth-Smallest; Rank-Query	The cleanest first benchmark where the whole problem is insert, delete, k-th, and count-smaller on one dynamic ordered set.

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Josephus Problem II	`CSES`	`Hard`	Circular Elimination	Simulation-Heavy; Data-Structure-Heavy	Find By Order; Alive Set Maintenance; Modulo Indexing	Find-By-Order; Josephus	A clean follow-up where the alive set stays explicit and find_by_order drives repeated circular removals.

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Salary Queries	`CSES`	`Medium`	Order Statistics	Query-Heavy; Data-Structure-Heavy	Pair-Key Wrapper; Order Of Key; Count In Range	Duplicate-Safe-Wrapper; Range-Count	A very teachable bridge from unique sets to duplicate-safe pair-key wrappers for count-in-range queries under updates.

Code	Title	Fit	Difficulty	Pattern	Note	Solution
`ORDERSET`	Order Statistic Set	`primary`	`medium`	-	Note	Code

python3 scripts/generate_problem_catalog.py