Heaps And Ordered Sets Ladder¶
This ladder is about operation choice: learn to pick heap, set, or multiset from what the problem needs, not from whatever container you used last.
Who This Is For¶
Use this ladder if:
- you know the syntax, but still choose the wrong structure
- duplicates and stale values still trip you up
- active-set problems feel ad hoc
Warm-Up¶
- current minimum / maximum maintenance
- scheduling with a heap
Target skill:
- recognize when “only the best candidate matters”
Core¶
- active interval sets
- sliding median style maintenance
- predecessor / successor queries
Target skill:
- reason from operations: insert, erase, top, predecessor, successor, duplicates
Stretch¶
- lazy deletion patterns
- compare heap and set solutions on the same task
- decide when PBDS or order-statistics logic is actually needed
Target skill:
- avoid overengineering while still choosing the right dynamic ordered structure
Retrieval Layer¶
- stale heap cleanup -> heap-lazy-delete.cpp
- predecessor in active multiset -> multiset-predecessor.cpp
- sliding median maintenance -> sliding-median-two-multisets.cpp
- exact rank /
k-th route -> PBDS / Order Statistics Tree ladder - quick reminder sheet -> Data structures cheatsheet
Exit Criteria¶
You are ready to move on when:
- you know when
multisetis required - you can explain why lazy deletion is often the easiest heap cleanup strategy
- you no longer use ordered sets when a plain heap is enough