topological sort

Topological sort orders a DAG so dependencies come first, the backbone of build systems, schedulers, and ML/data pipeline DAGs. The signal is Kahn's algorithm (or DFS) plus cycle detection. Here is the answer.

Course Schedule reduces to one question: is the prerequisite graph a DAG? The signal is spotting the graph framing and using topological sort or DFS to detect a cycle. Here is the answer.

The words encode a partial order between characters. Turn each adjacent pair into a directed edge, then topologically sort. The traps are the prefix edge case and detecting contradictions. Here is the full solution with cycle handling.

Sierra's signature build screen: cells hold values or formulas referencing other cells, and editing one must recompute its dependents without infinite loops. The signal is the dependency graph plus cycle detection. Here is the topological-eval design.