Silver

Introduction to Prefix Sums

Somewhat Frequent

Computing range sum queries in constant time over a fixed 1D array.

More on Prefix Sums

Not Frequent

Max subarray sum, prefix sums in two dimensions, and a more complicated example.

Custom Comparators and Coordinate Compression

Somewhat Frequent

Using a custom comparator to sort custom objects or values in a non-default order, and compressing values from a large range to a smaller one.

Two Pointers

Not Frequent

Iterating two monotonic pointers across an array to search for a pair of indices satisfying some condition in linear time.

More Operations on Sorted Sets

Not Frequent

Finding the next element smaller or larger than a specified key in a set, and using iterators with sets.

(Optional) C++ Sets with Custom Comparators

Rare

Incorporating custom comparators into standard library containers.

Greedy Algorithms with Sorting

Somewhat Frequent

Solving greedy problems by sorting the input.

Binary Search

Somewhat Frequent

Binary searching on arbitrary monotonic functions and built-in functions for binary search.
Updated: Last month

Graph Traversal

Very Frequent

Traversing a graph with depth first search and breadth first search.
Updated: Last month

Flood Fill

Somewhat Frequent

Finding connected components in a graph represented by a grid.

Introduction to Tree Algorithms

Not Frequent

Introducing a special type of graph: trees.

Introduction to Functional Graphs

Not Frequent

Directed graphs in which every vertex has exactly one outgoing edge.

Intro to Bitwise Operators

Somewhat Frequent

Six bitwise operators and the common ways they are used.

Additional Practice for USACO Silver

Final tips for Silver and additional practice problems.