Logic Masters Deutschland e.V.

Quorum Rings

Rules:

1. Standard: Normal sudoku rules apply.

2. Diagonal: Digits may not repeat on either main diagonal.

3. Killer: Digits in a cage must sum to the clue in the top left corner. Digits may not repeat within a cage.

4. Little killer: The clue outside the grid gives the sum of digits on the indicated diagonal. Digits may repeat on the diagonal if allowed by other rules.

Hint 1:
Question: If any digits don't appear on the Phistomefel ring, where can they appear on the main diagonal?
Answer: If a digit is missing from the ring, it must appear in r5c5 to ensure it is on both diagonals. In other words, at most one digit may be missing from the ring, and the eight digits which are not in r5c5 must all appear in the ring.

Hint 2:
The fact given by hint 1 is true for the r19c19 and r28c28 Phistomefel rings as well.

Solve online

Simon's solve on CTC (app version as used in the video)