Foundations -> STL Basics

Container and algorithm fluency: build the habit of reaching for vector, set, map, iterators, and standard algorithms before writing custom machinery.

• Topic slug: foundations/stl
• Tutorial page: Open tutorial
• Ladder page: Open ladder
• Repo problems currently tagged here: 1
• Repo companion pages: 0
• Curated external problems: 8

Microtopics

• vector
• pair-and-tuple
• iterators
• sort
• lower_bound
• set-and-multiset
• map
• priority_queue

Learning Sources

Source	Type
cppreference containers	Primary
cppreference algorithms	Primary
USACO Guide	Reference

Practice Sources

Source	Type
CSES Problem Set	Practice
Codeforces data structures tag	Practice

Curated External Problems

Warm-Up

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Distinct Numbers	CSES	Easy	-	Data-Structure-Heavy; Implementation-Heavy	Arrays; Sets; Hashing Basics	Set; Deduplication; Frequency; Sort; Unique	A straightforward entry point for seeing why a set or hash set is useful.

Core

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Restaurant Customers	CSES	Easy	-	Modeling-Heavy; Implementation-Heavy	Sorting; Event Processing; Prefix Counts	Events; Sweep Line; Sorting	Useful for learning to model arrivals and departures as events and process them cleanly.
Towers	CSES	Medium	-	-	-	Multiset; Lower Bound; Patience	Teaches the lower_bound pattern on a multiset.

Classics

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Concert Tickets	CSES	Medium	-	Data-Structure-Heavy; Greedy-Heavy	Sorting; Ordered Multiset Ideas; Greedy Matching	Multiset; Lower Bound	A canonical ordered-container problem that rewards knowing lower_bound-style queries.
Room Allocation	CSES	Medium	-	Data-Structure-Heavy; Greedy-Heavy	Sorting; Priority Queues; Interval Scheduling	Priority-Queue; Intervals; Assignment	A strong multiset/priority-queue assignment problem that feels very STL-native.
Traffic Lights	CSES	Medium	-	Data-Structure-Heavy	Ordered Sets; Interval Reasoning; Sorting	Ordered-Set; Intervals; Updates; Neighbors	A classic ordered-set exercise with dynamic insertions and interval maintenance.

Advanced

Problem	Source	Difficulty	Context	Style	Prerequisites	Tags	Why it fits
Sliding Window Cost	CSES	Hard	-	Data-Structure-Heavy	Multisets; Two Pointers; Median Reasoning	Median; Sliding-Window; Absolute-Deviation	A deeper ordered-container problem that pairs median maintenance with cost accounting.
Sliding Window Median	CSES	Hard	-	Data-Structure-Heavy; Query-Heavy	Multisets; Two Pointers; Balanced Data Structures	Multiset; Median; Sliding-Window	A demanding but standard STL benchmark for maintaining order statistics over a moving window.

Repo Problems

Code	Title	Fit	Difficulty	Pattern	Note	Solution
DISTINCTNUMBERS	Distinct Numbers	primary	easy	sort unique; container deduplication; stl algorithms	Note	Code

Regeneration

python3 scripts/generate_problem_catalog.py