Cycle Detection in Directed Graphs | Dataford Interview Questions

Juspay Hyper can model payment-processing steps as directed dependencies, where an edge from step A to step B means A must complete before B starts. Given this dependency graph, determine whether it contains a directed cycle.

Implement has_cycle(graph). Return True if any directed cycle exists, otherwise return False.

Formal Specification

Input: graph, a dictionary mapping each node name, represented by a string, to a list of neighboring node names.
Output: A boolean. Return True when the graph contains at least one directed cycle; otherwise return False.
Every node referenced as a neighbor is guaranteed to appear as a key, possibly with an empty neighbor list.
The graph may be disconnected and may contain self-loops.

Constraints

1 <= number of nodes <= 10^5
0 <= number of edges <= 2 * 10^5
Node names are non-empty strings
Every referenced neighbor appears as a graph key
Duplicate edges may be present

Function Signature

def has_cycle(graph):

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