Strongly connected components refer to connected components in a directed graph, and is useful to simplify a directed graph, for instance, merging all vertices in the same strongly connected components to be a big vertex, could produce a Directed Acyclic Graph (DAG) with less number of vertices. This post documents two well-known algorithms (i.e., Kosaraju’s Algorithm and Tarjan’s Algorithm) that solve the strongly connected component problem.

Weakly connected components refer to connected components in an undirected graph, also known as friend circle problem. This post documents three common solutions to figure out the number of connected components in graphs.

I had a post, Container Types in C++, where I introduced a bit about one of the C++ containters std::map.
Yesterday I ran into an interesting use case of map, namely, I wanted to use map with customized key, bi-match unsigned integer pair. This post talks about the way to customize key for std::map, and issues and solution to get a bi-match unsigned integer pair work correctly as the key.

DFS (Deepth First Search) and BFS (Breadth First Search) are two approaches to traverse tree. It is relatively easy to implement BFS in an iterative manner (with the help of queue). While it is a bit challenging to do DFS without reursion.