How should I practice Diff Two Filesystem Hash Trees?

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Diff Two Filesystem Hash Trees

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Problem statement

Two finite filesystems are represented by parallel path and UTF-8 text arrays. Each path is a unique normalized absolute file path; parent directories are implicit.

Return every file path whose presence or content differs between the two filesystems, sorted lexicographically. A path that appears on only one side is changed.

This is the observable diff operation for a filesystem Merkle tree: equal subtree hashes may be skipped, while unequal leaves are reported. Hashes are an optimization and must not change exact content equality.

Function

diffFileSystems(pathsA: String[], contentsA: String[], pathsB: String[], contentsB: String[]) → String[]

Examples

Example 1

pathsA = ["/a.txt","/docs/b.txt"]contentsA = ["one","two"]pathsB = ["/a.txt","/docs/b.txt"]contentsB = ["one","changed"]return = ["/docs/b.txt"]

Only the nested file changed.

Example 2

pathsA = ["/a","/gone"]contentsA = ["x","old"]pathsB = ["/a","/new"]contentsB = ["x","fresh"]return = ["/gone","/new"]

Removed and added paths are both reported in lexical order.

Example 3

pathsA = []contentsA = []pathsB = []contentsB = []return = []

Two empty filesystems have no changed files.

Constraints

0 <= pathsA.length == contentsA.length <= 100000 and likewise for B.
Paths are unique within each side and contain at most 500 UTF-8 bytes.
The combined content size is at most 2 * 10^6 UTF-8 bytes.
Hash equality may prune work only when exact equality remains collision-safe.