Topological build order for services

Python data engineering interview problem. Difficulty: advanced. Pattern: Graphs. About 20 minutes. Part of the Pro drill bank.

Services must build in an order that respects dependencies: a library before the app that imports it. Produce a valid topological order.

Return a topological build order for a service dependency map.

Requirements

• A service appears only after the services it depends on.
• If a cycle exists, follow the tests (empty list vs error).

Constraints

• deps: adjacency map.
• Isolated services can appear anywhere relative to unrelated chains.
• Multiple valid orders may exist; pick one the tests accept.

Examples

Input: build_order({'app': ['lib'], 'lib': []}) Output: ['lib', 'app'] This input follows the stated rules and produces this output.

Topics: lakebench, python, graphs.

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