# Containers

This week will be about containers (collections).

Demonstrations:

 1. ‹freq›      – a word frequency histogram
 2. ‹dfs›       – reachability using recursive depth-first search
 3. ‹closure›   – closure properties of relations
 4. ‹bfs›       – find the nearest matching node

Elementary exercises:

 1. ‹unique›    – remove duplicated entries from a vector
 2. ‹reflexive› – compute a reflexive closure of a relation
 3. ‹normalize› – scale an input vector into a 0-1 range

Free exercises:

 1. ‹mode›      – find the mode (most common value) in a vector
 2. ‹buckets›   – sort items into buckets based on an attribute
 3. ‹shortest›  – shortest distances in an unweighted graph

Graded exercises:

 1. ‹brackets›  – check that brackets in a string balance out
 2. ‹connected› – decompose a graph into connected components
 3. ‹dag›       – check whether a graph is acyclic (dfs again)
 4. ‹rel›       – a tiny bit of relational algebra
 5. ‹numbers›   – a slightly enriched set of numbers
 6. ‹bipartite› – bipartiteness checking using BFS