12x12 Queens Puzzle #191
Difficulty: medium. Place 12 queens on this 12x12 board so that no two share a row, column or color region and none touch — including diagonally. This puzzle has exactly one solution, and it has been verified solvable by deduction alone: the complete 21-step reasoning is written out below.
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Step-by-step solution for puzzle #191
What follows is a complete solve of puzzle #191, worked the way a person works it rather than the way a computer does. It runs to 21 deductions — 12 queen placements and 9 elimination steps that narrow the board between them. Each step names the rule that forces it, so nothing below is a guess, and the hardest idea required is the region shadow.
Techniques this board needs: last square in a region, region shadow, region confined to one line, last square in a column.
Show the full walkthrough (16 steps) — contains the solution
Step 1. Only row 8, column 9 is still open in khaki, and since each colour must take a queen, that settles it. That clears row 8, column 9, the rest of the khaki region and every square adjacent to it — diagonals included.
Step 2. Indigo is down to 5 candidates in rows 1–3, columns 6–8, and they overlap enough to cover 1 square elsewhere. Cross those out without deciding anything about indigo itself.
Step 3. Amber cannot leave column 11 — every one of its open squares (2 open squares) sits there. That column belongs to amber, so every square in it owned by another colour is dead: 13 squares in all.
Step 4. Wherever blue ends up among its 2 squares, the same squares fall within reach of it — 3 squares in total, impossible regardless of how the colour resolves.
Step 5. Mint cannot leave column 12 — every one of its open squares (2 open squares) sits there. That column belongs to mint, so every square in it owned by another colour is dead: 7 squares in all.
The board after step 5 — 1 of 12 queens placed. Step 6. The teal region has 3 squares left, spread across rows 11 and 12, columns 3 and 4. You do not need to know which of them takes the queen: every one of those options attacks the same 3 squares, so they can be crossed out now.
Step 7. Only row 12, column 2 is still open in rose, and since each colour must take a queen, that settles it. Everything else in row 12, in column 2, in rose and in the ring around that square is now dead.
Step 8. The teal region is down to one open square, at row 11, column 4. Every colour holds exactly one queen, so that square is forced. Row 11 and column 4 are now spoken for, along with the squares touching that queen.
Step 9. Red cannot leave column 1 — every one of its open squares (4 open squares) sits there. That column belongs to red, so every square in it owned by another colour is dead: 5 squares in all.
Step 10. The orange region is down to one open square, at row 9, column 3. Every colour holds exactly one queen, so that square is forced. Cross out the whole of row 9 and column 3, the remaining orange squares, and the ring of neighbours around row 9, column 3.
Step 11. Sea green cannot leave column 10 — every one of its open squares (3 open squares) sits there. That column belongs to sea green, so every square in it owned by another colour is dead: 1 square in all.
The board after step 11 — 4 of 12 queens placed. Step 12. The blue region is down to one open square, at row 3, column 8. Every colour holds exactly one queen, so that square is forced. Row 3 and column 8 are now spoken for, along with the squares touching that queen.
Step 13. Only row 4, column 12 is still open in mint, and since each colour must take a queen, that settles it. That clears row 4, column 12, the rest of the mint region and every square adjacent to it — diagonals included.
Step 14. Indigo is down to 2 candidates in rows 1 and 2, columns 6 and 7, and they overlap enough to cover 2 squares elsewhere. Cross those out without deciding anything about indigo itself.
Step 15. The slate region has 3 squares left, spread across rows 2, 5, and 6, columns 5 and 6. You do not need to know which of them takes the queen: every one of those options attacks the same 3 squares, so they can be crossed out now.
Step 16. From here the board cascades. Keep alternating the region sweep and the line sweep and 6 queens fall out in order without any new idea being needed: indigo has one square left, so its queen takes row 1, column 7; amber has one square left, so its queen takes row 2, column 11; column 5 is down to one square, putting a queen on row 7, column 5; slate has one square left, so its queen takes row 5, column 6; red has one square left, so its queen takes row 6, column 1; sea green has one square left, so its queen takes row 10, column 10. After each one, clear that row, that column, the rest of the colour and the ring of neighbours before looking for the next. The last of them seats the queen on row 10, column 10.
The board after step 16 — 12 of 12 queens placed.
That completes the board: 12 queens seated, one in every row, one in every column and one in every colour, with no two of them touching. Notice that nothing in the sequence above required a guess — each placement followed from an elimination already on the grid, which is what “single solution, solvable by logic” actually means in practice.
About 12x12 Queens puzzle #191
12x12 puzzle #191 is rated medium. Twelve colored regions cover its 144 squares, and your job is to seat twelve queens so that every row, column and color contains exactly one — with no queen touching another, including diagonally.
Puzzle #191 has been checked to admit exactly one arrangement of queens, and every step toward it is deducible from what is already on the board. There is no point at which you are expected to pick a square and hope. The only thing that differs between boards is how quickly the first certainty surfaces, and that depends entirely on the shapes the colors happen to take here.
How the colors divide this board
From smallest to largest, the regions on puzzle #191 are: khaki (1 square), amber (2 squares), rose (2 squares), teal (3 squares), indigo (5 squares), red (7 squares), mint (9 squares), blue (11 squares), orange (14 squares), pale yellow (29 squares), sea green (30 squares), slate (31 squares). An even split would hand every color 12 squares, so the khaki region is running 11 squares under that average while the slate region is the roomiest area on the grid with 31 squares.
One queen per color, regardless of acreage: that is what turns this uneven split into a solving order. Khaki is working with 1 square while slate has 31 to spare, a gap of 30. Attack the cramped end and the roomy regions tend to resolve themselves.
A region's outline can constrain it more than its size does. Here amber is the most solid, filling 100% of its 2×1 box, and mint the most diffuse at 50% of its 6×3 box. Solid blocks give clean eliminations; diffuse ones spread across the board and stay open longer.
Region by region
Here is the full footprint of every color on puzzle #191, smallest first. Reading these spans before you place anything is the quickest way to see which parts of the grid are genuinely contested.
Khaki occupies 1 square within rows 8–8, columns 9–9. It never leaves row 8, so its queen is locked to that row.
Amber: 2 squares across rows 1–2, columns 11–11. It sits wholly inside column 11, so its queen must be in that column.
Rose covers 2 squares, spanning 2 rows and 1 column (rows 11–12, columns 2–2). It sits wholly inside column 2, so its queen must be in that column.
Teal occupies 3 squares within rows 11–12, columns 3–4.
Indigo: 5 squares across rows 1–3, columns 6–8.
Red covers 7 squares, spanning 5 rows and 2 columns (rows 3–7, columns 1–2).
Mint occupies 9 squares within rows 1–6, columns 10–12.
Blue: 11 squares across rows 1–6, columns 8–10.
Orange covers 14 squares, spanning 6 rows and 4 columns (rows 7–12, columns 1–4).
Pale yellow occupies 29 squares within rows 4–12, columns 4–8.
Sea green: 30 squares across rows 5–12, columns 7–12.
Slate covers 31 squares, spanning 8 rows and 7 columns (rows 1–8, columns 1–7).
Where to start on this board
Begin where the choices are fewest. On this board that means khaki, which owns just 1 square inside a 1×1 window running from row 8 to row 8 and column 9 to column 9. A queen is guaranteed somewhere in there, so every line that window crosses is under pressure from the very first move.
Because khaki never leaves row 8, its queen must be in that row — and that instantly settles row 8 for everyone else. Sweep along it and X out every square that is not khaki. Then look at which colors just lost ground: on a grid this size that one observation usually forces a second region within a move or two.
Work outward to the other flat regions next. Amber, rose and teal are no more than two rows tall, so their queens are confined to a narrow band. When two flat regions overlap the same pair of rows, those rows are spoken for and every other color is locked out of both — the single most productive pattern in the game, and it is live on this board.
The tightest lines on puzzle #191
A quick way to find the next move is to count how many different colors touch each line. On this board, rows 9 and 10 are the narrowest, touched by only 3 colors. Columns 5 and 12 are the tightest columns, with 2 colors.
Those lines matter because a row touched by few colors gives its queen away sooner. If a row meets only 3 colors, then one of those regions has to own it, and every other region is competing for the remaining 11 rows. By contrast row 6 meets 6 colors — the most crowded line here, and the one least likely to resolve early. Spend your attention accordingly.
Working through the middle game
Once two or three queens are down, the board changes character. Each queen removes an entire row, an entire column and the ring of up to eight squares around it, so the grid shrinks faster than most people expect. The habit that pays here is marking rather than remembering: after every placement, cross out the full row, the full column and all eight neighbours before hunting for the next move.
With twelve queens to seat and twelve regions competing over 144 squares, keep two questions in rotation. Does any region now have exactly one open square left? That queen is forced. Does any row or column now have exactly one open square left? That queen is forced too. Alternating between the region view and the row-and-column view is what keeps a solve moving, and it is the clearest difference between players who finish 12x12 boards quickly and players who stall halfway.
Resist the plausible-looking queen. On #191 every correct placement has a stated reason behind it, and any move you cannot justify is a guess wearing a disguise. Backing out of a wrong guess on a single-solution board takes far longer than finding the real deduction would have.
Why puzzle #191 is rated medium
The rating reflects how much the board concedes up front. Puzzle #191 has four regions confined to a single row or column, its smallest color holds 1 square, its tightest row meets just 3 colors, and the gap between its largest and smallest regions is 30 squares. Flat, lopsided boards open quickly; even, sprawling ones make you earn the first placement.
Nothing about the rating involves computation or chance. Each grid has a single solution reachable by pure logic; the rating simply measures how far ahead you have to reason. Easy boards resolve a queen every step or two, while hard ones can ask you to carry three unfinished lines of thought before any of them pays off.
When a board plays tougher than its label, look for a missed mark before you look for a clever deduction. Walk back over every queen you have placed and confirm the full row, the full column and all eight surrounding squares are crossed out. The diagonal neighbours are the ones players skip, and a single skipped diagonal will hide the next forced move indefinitely.
Techniques that work well at 12x12
At 12x12 you are managing 144 squares, and holding the whole board in your head will not work. Split it into quadrants and solve locally. Most useful deductions on a grid this large are regional — a color pinched between two placed queens, or a band of rows that two regions must share. Trust the marks on the board over your memory.
Whatever the grid size, the pairing rule is the technique to internalise. When a pair of regions is boxed into the same pair of rows, they split those rows between them and nobody else may enter — and the same holds for columns, or for any n regions confined to n lines. Look for an instance of it around column 5 on this board.
As a sanity check rather than a spoiler: the finished solution to #191 puts 4 queens on the outer border and 8 queens in the interior, with none in a corner. If your part-finished grid has queens bunched into one area while whole stretches sit empty, something probably went wrong a few moves back.
How to play Queens
- The board is an N×N grid divided into N colored regions.
- Place exactly one queen (♛) in each row, each column, and each colored region.
- No two queens may touch each other — not horizontally, vertically, or diagonally.
- Tap once to mark a square with an X (where a queen can't go), tap again to place a queen, and once more to clear it.
- There is always exactly one valid solution. Use logic, never guessing, to find it.
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Questions about this puzzle
How hard is 12x12 Queens puzzle #191?
Puzzle #191 is rated medium. Its smallest color region holds 1 square, its tightest row is touched by 3 colors, and four of its regions are confined to a single row or column, which gives you a forced move early.
Does 12x12 puzzle #191 have only one solution?
Yes. Every puzzle in the 12x12 collection, including #191, has been verified to have exactly one valid arrangement of twelve queens, and it can always be reached by logic alone — no guessing or backtracking needed.
Where should I place my first queen on puzzle #191?
Start with the khaki region — the most constrained color on this board, with 1 square spanning rows 8–8 and columns 9–9. Narrowing the smallest region first removes the most squares elsewhere on the grid.