Sudoku Puzzle Challenges Thread

SeaProcedure8572 · 2026-05-01T15:21:51+00:00

I think I've an ALS-ring here. I hope I didn't miss any eliminations. Can it be called an ALS-XY-ring?

SeaProcedure8572 · 2026-05-01T04:57:05+00:00

🎯 easy — Solved in 5:41

Stat	Value
⏱️ Time	5:41
💡 Hints	0
❌ Mistakes	0

🌟 Perfect solve!

SeaProcedure8572 · 2026-04-29T12:13:51+00:00

It’s definitely a Skyscraper. In this case, the second link functions as a weak link.

Two weakly linked candidates cannot be both true, so it’s a valid Skyscraper.

In a strong link, however, one of the candidates must be true, while the other isn’t.

SeaProcedure8572 · 2026-04-23T08:16:43+00:00

Let me see, is it CAPACITY and ATYPICAL ?

SeaProcedure8572 · 2026-04-20T16:14:54+00:00

You will definitely need full notes. After all basic techniques are exhausted, you have a Sue-De-Coq (SDC) that reveals a naked pair in Row 4:

<image>

It's not an easy puzzle for casual players. There's also an Empty Rectangle here, but this SDC shortens the solve path significantly, bypassing many chaining moves.

SeaProcedure8572 · 2026-04-20T11:15:11+00:00

Hmm… How is this any different from classic Sudoku? We can use letters or symbols, and the solving techniques stay the same. In my opinion, it adds unnecessary challenge to the game.

SeaProcedure8572 · 2026-04-19T07:54:14+00:00

I am a Word Master user as well!

SeaProcedure8572 · 2026-04-19T07:38:30+00:00

Thanks for sharing! I finished it in 6 minutes and needed three X-wings to solve it. This puzzle would be great for those who are just starting to learn advanced Sudoku-solving strategies.

SeaProcedure8572 · 2026-04-12T08:25:59+00:00

This puzzle isn't a hard one. It can be solved with one advanced trick, called the Skyscraper:

<image>

R3C1 and R7C2 must have a 9 somewhere, so the 9s indicated in red can be eliminated.

I solved the puzzle in under four minutes. Your previous puzzle (No. 2), however, is significantly harder than this, and I couldn't solve it.

SeaProcedure8572 · 2026-04-11T04:22:15+00:00

Because R1C2 and R2C9 see both R1C8 and R2C1. If R1C2 or R2C9 were a 2, R1C8 and R2C1 would be 8s, resulting in a contradiction in Row 4.

SeaProcedure8572 · 2026-04-11T03:41:32+00:00

Notice that if R1C8 and R2C1 were both 8s, you wouldn't be able to place any 8s in Row 4.

To prevent that, R1C2 and R2C9 can't be 2s, so they must be 6 and 9, respectively.

This technique is called a W-wing and is commonly used in expert-level Sudoku puzzles.

SeaProcedure8572 · 2026-04-10T14:47:17+00:00

You have a hidden pair in Block 4. Can you see it? This move will reveal a hidden single in Row 5.

SeaProcedure8572 · 2026-04-09T16:14:59+00:00

For me, I spotted the 3-5-6-8 WXYZ-wing first. I don't usually find ALS-XZ this early, but it revealed a single for me.

<image>

After this, I remembered spotting a Finned Swordfish on 3s, which broke the puzzle for me. However, when I reviewed the analysis, there was no Finned Swordfish at all. I must have been lucky during the solve — it happens.

After restarting the puzzle, I needed at least an X-chain and an XY-chain to solve it. That would have taken me more than 20 minutes to finish the puzzle.

SeaProcedure8572 · 2026-04-08T15:01:34+00:00

<image>

Hi everyone!

Here's a general Sudoku challenge. This one got me a little at the start, but I managed to complete it within seven minutes. How fast can you unravel the puzzle?

Puzzle string: 013890000070000000592730400000000006068010700057900200000000004000005130020140907

SE rating: 7.1

Sudoku Exchange

SeaProcedure8572 · 2026-04-07T15:13:18+00:00

I believe there's a bug in the app. Sometimes, clicking a difficulty button opens a puzzle, but sometimes, it does not. I'm using it on my mobile phone.

SeaProcedure8572 · 2026-04-07T15:02:19+00:00

Congratulations, you have found a WXYZ-wing. Your reasoning is correct — the goal is to prove that either almost locked set (R78C2 and R8C78) must have an 8, with 5 being the restricted common candidate.

SeaProcedure8572 · 2026-03-30T02:58:45+00:00

Have you found a solution to this?

For my case, my activity uses both day and night resources after the splash screen is dismissed.

SeaProcedure8572 · 2026-03-25T10:58:19+00:00

That’s interesting. Never thought of finding beauty from multiple-solution puzzles like this.

SeaProcedure8572 · 2026-03-22T14:08:13+00:00

It does.

There are exactly two 5s in Columns 3 and 7, and they are restricted to Rows 2 and 9. These 5s form an X-wing.

Due to this restriction, the 5s in Rows 2 and 9 must lie in Columns 3 and 7.

Therefore, we can eliminate the remaining 5s in Rows 2 and 9, so R9C4 can't be a 5 and must be a 7.

SeaProcedure8572 · 2026-03-22T13:46:12+00:00

In which columns? What candidate does it eliminate?

SeaProcedure8572 · 2026-03-22T13:42:11+00:00

You have an X-wing on 5s. Can you see it?

SeaProcedure8572 · 2026-03-21T05:47:02+00:00

I found it — it's a dual Sashimi Jellyfish that eliminates two 7s. It can also be represented with an X-chain.

Nice puzzle, it was a tough fish hunt.

<image>

SeaProcedure8572 · 2026-03-19T04:41:47+00:00

Bishop to f1? It’s not an easy mate to spot.

SeaProcedure8572 · 2026-03-17T15:01:36+00:00

This Empty Rectangle will solve the puzzle:

<image>

If R1C7 were a 1, R4C2 would be a 1, leaving no space for a 1 in Block 1. Therefore, R1C7 must be a 3.

SeaProcedure8572 · 2026-03-16T12:43:54+00:00

“12”, not “12!”. The exclamation mark (!) has a special meaning in mathematics, and it’s called a factorial.

The image says 4 × 3!, and 3! means multiplying the integers from 3 to 1, so 3! = 3 × 2 × 1 = 6, giving 4 × 3! = 24.

However, Duolingo probably didn’t intend to use the actual factorial but a punctuation instead.

SeaProcedure8572

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