1. find-goal-undirected: Find goal in an undirected graph.
2. find-goal-directed-a-b: Get from a to b in a directed graph.
3. find-goal-directed-b-a: Reverse of #2.
4. detect-cycle: Detect a cycle (not DAG).
Source used to generate images: https://github.com/athleticus/graph-search-visualizer