Uniform cost search takes into account the cost associated with an action, and can be implemented with a priority queue. Heuristics extimate the cost of the remaining path to the goal; the Manhattan distance is an example of an admissible heuristic.

Discussion of imperative, functional, and object-oriented programming styles. State machines are introduced, using a turnstile as an example.

Two search algorithms are introduced, depth-first search and breadth-first search. Pruning rules (including dynamic programming) are also considered, so that the same state is not visited repeatedly.