Group duplicate files by content

## Problem You are given a list of files in a filesystem. Each file has: - a full path (string) - a file size in bytes (integer) - file contents (conceptually; assume you can stream/read the file when needed) Two files are **duplicates** if their contents are identical (byte-for-byte), regardless of file name or directory. **Task:** Return groups of duplicate files. Each group should contain the full paths of files that have identical content, and groups of size 1 should be omitted. ### Constraints / Expectations - There can be millions of files. - Reading file contents is expensive. - Aim to minimize unnecessary content reads / hashing. ### Follow-ups 1. Describe an approach that avoids hashing every file if most files are unique. 2. How would you handle extremely large files (e.g., >GB) without loading them fully into memory? 3. If hash collisions are a concern, how do you confirm duplicates? ### Example Input files (path, size, content): - /a/x.txt, 4, "ABCD" - /b/y.txt, 4, "ABCD" - /c/z.txt, 4, "WXYZ" - /d/w.txt, 7, "1234567" Output: - ["/a/x.txt", "/b/y.txt"]