How should I practice Longest Name Chain in a Directed Acyclic Graph?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Oscar Health phone screen problems in FastPrep.

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Longest Name Chain in a Directed Acyclic Graph

Oscar Health● MediumFULLTIMEPHONE SCREEN

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Problem statement

Each row [from, to] in edges is a directed connection between two names. The complete graph is guaranteed to be acyclic.

A name chain is a directed path. Its length is the number of names on that path, including both endpoints. Return the maximum chain length. Duplicate rows describe the same directed edge and must not increase the result. Return 0 when edges is empty.

Function

longestNameChain(edges: String[][]) → int

Examples

Example 1

edges = [["a","b"],["b","c"],["d","e"]]return = 3

The longest chain is a -> b -> c, which contains three names.

Example 2

edges = [["amy","bo"],["amy","cy"],["bo","dee"],["cy","dee"],["dee","eve"]]return = 4

Either branch from amy reaches eve through four names.

Example 3

edges = []return = 0

No names are present.

Constraints

0 <= edges.length <= 100000.
Every row contains exactly two nonempty names.
Names contain 1 to 40 visible ASCII characters.
The graph described by the distinct edges is a directed acyclic graph.