topological sort

Topological sort arranges a DAG so dependencies come first, the backbone of build systems, schedulers, and ML/data pipeline DAGs. Interviewers look for Kahn's algorithm (or DFS) plus cycle detection. The answer follows.

Course Schedule collapses to a single question: is the prerequisite graph a DAG? The signal is seeing the graph framing and applying topological sort or DFS to detect a cycle. Here is the answer.

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

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