Closed Loops in a Book-Swap Club

Problem

In a book-swap club, every entry in `book_swaps` records one member lending a book of `page_count` pages to exactly one other member. Some of these lending relationships form closed loops: member A lends to B, B lends to C, and C lends back to A, so each member in the loop both gives and receives exactly once. Find every such circular loop and, for each one, report `chain_length` (how many members are in the loop) and `total_pages` (the sum of the page counts around the loop). Each distinct loop must appear exactly once regardless of where you start tracing it. Order by `chain_length` descending, then `total_pages` descending.

Tables

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 2 rows with the columns chain_length, total_pages.

Starter code (SQL)

SELECT *
FROM book_swaps;

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