Dependency Graph Build Order | Dataford Interview Questions

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Problem

The SoFi app is assembled from software components with prerequisite relationships. Given all components and their dependencies, return an order in which every component can be built after its prerequisites. If a circular dependency makes a complete build impossible, return an empty list.

Formal Specification

Implement build_order(components, dependencies).

components is a list of unique strings.
dependencies is a list of two-element lists [prerequisite, component], meaning prerequisite must appear earlier than component.
Return a list containing every component exactly once in a valid build order, or [] if no complete order exists.
Components without dependencies may appear anywhere that preserves all dependency rules. When multiple components are available, process them in their original order from components.

Constraints

1 <= len(components) <= 10^4
0 <= len(dependencies) <= 3 * 10^4
Every dependency references a component in components
Component names are unique, non-empty strings
Dependency pairs are unique and contain distinct components

Function Signature

def build_order(components, dependencies):