12x12 Queens Puzzle #298
Difficulty: easy. 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 27-step reasoning is written out below.
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Step-by-step solution for puzzle #298
What follows is a complete solve of puzzle #298, worked the way a person works it rather than the way a computer does. It runs to 27 deductions — 12 queen placements and 15 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 proof by contradiction.
Techniques this board needs: region confined to one line, last square in a region, pairing argument on rows, proof by contradiction, region shadow, pairing argument on columns.
Show the full walkthrough (19 steps) — contains the solution
Step 1. Blue cannot leave column 6 — every one of its open squares (2 open squares) sits there. That column belongs to blue, so every square in it owned by another colour is dead: 14 squares in all.
Step 2. The mint region is down to one open square, at row 4, column 8. Every colour holds exactly one queen, so that square is forced. Cross out the whole of row 4 and column 8, the remaining mint squares, and the ring of neighbours around row 4, column 8.
Step 3. Only row 3, column 6 is still open in blue, and since each colour must take a queen, that settles it. Everything else in row 3, in column 6, in blue and in the ring around that square is now dead.
Step 4. All of the rose region's remaining squares (3 open squares) lie in row 12. Its queen therefore has to be somewhere on that row, which means no other colour may use it: 8 squares come off.
Step 5. Sea green and teal are now boxed into rows 10 and 11 and nothing else. That is 2 colours needing 2 rows, so they fill those rows between them — which locks every remaining colour out and removes 11 squares at once.
The board after step 5 — 2 of 12 queens placed. Step 6. All of the orange region's remaining squares (3 open squares) lie in row 9. Its queen therefore has to be somewhere on that row, which means no other colour may use it: 7 squares come off.
Step 7. Khaki cannot leave row 8 — every one of its open squares (2 open squares) sits there. That row belongs to khaki, so every square on it owned by another colour is dead: 10 squares in all.
Step 8. Now a short proof by contradiction. Suppose the indigo queen went to row 1, column 1. Follow the forced moves that would create and the red region is left with nowhere to put its queen — impossible. So that square is ruled out for good.
Step 9. Test row 1, column 2 for indigo: place a queen there, run the forced consequences through, and the red region is left with nowhere to put its queen. The assumption breaks, so the square is eliminated.
Step 10. Now a short proof by contradiction. Suppose the indigo queen went to row 1, column 3. Follow the forced moves that would create and the red region is left with nowhere to put its queen — impossible. So that square is ruled out for good.
The board after step 10 — 2 of 12 queens placed. Step 11. Test row 1, column 4 for indigo: place a queen there, run the forced consequences through, and the red region is left with nowhere to put its queen. The assumption breaks, so the square is eliminated.
Step 12. Now a short proof by contradiction. Suppose the indigo queen went to row 2, column 1. Follow the forced moves that would create and the red region is left with nowhere to put its queen — impossible. So that square is ruled out for good.
Step 13. Test row 2, column 2 for indigo: place a queen there, run the forced consequences through, and the red region is left with nowhere to put its queen. The assumption breaks, so the square is eliminated.
Step 14. Now a short proof by contradiction. Suppose the indigo queen went to row 2, column 3. Follow the forced moves that would create and the red region is left with nowhere to put its queen — impossible. So that square is ruled out for good.
The board after step 14 — 2 of 12 queens placed. Step 15. Test row 2, column 4 for indigo: place a queen there, run the forced consequences through, and the red region is left with nowhere to put its queen. The assumption breaks, so the square is eliminated.
Step 16. The indigo region is down to one open square, at row 1, column 5. Every colour holds exactly one queen, so that square is forced. Row 1 and column 5 are now spoken for, along with the squares touching that queen.
Step 17. Red is down to 6 candidates in rows 5–7, columns 2, 3, 4, and 7, and they overlap enough to cover 1 square elsewhere. Cross those out without deciding anything about red itself.
Step 18. Here is the pairing argument. The slate, khaki, sea green, and rose regions have no open squares outside columns 1–4 — 4 colours confined to 4 columns. Between them they must take one column each, in some order, so every other colour is shut out of all of them: 5 squares come off in one stroke.
Step 19. From here the board cascades. Keep alternating the region sweep and the line sweep and 9 queens fall out in order without any new idea being needed: red has one square left, so its queen takes row 6, column 7; slate has one square left, so its queen takes row 5, column 1; khaki has one square left, so its queen takes row 8, column 2; teal has one square left, so its queen takes row 11, column 9; amber has one square left, so its queen takes row 2, column 10; orange has one square left, so its queen takes row 9, column 12; pale yellow has one square left, so its queen takes row 7, column 11; rose has one square left, so its queen takes row 12, column 3; sea green has one square left, so its queen takes row 10, column 4. 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 4.
The board after step 19 — 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 #298
Board #298 of the 12x12 bank carries a easy rating. Its 144 squares are shared between twelve colored regions, and the solution places twelve queens: one per row, one per column, one per region, none of them side by side or corner to corner.
Like every board on this site, #298 has been verified to have exactly one valid solution, and that solution is reachable by deduction alone. You never have to guess and then unwind; every queen can be justified by something already visible on the grid. What changes from puzzle to puzzle is where the first certainty appears and how long the chain of reasoning runs before the next one — and that is entirely a product of how these particular colors are shaped.
How the colors divide this board
From smallest to largest, the regions on puzzle #298 are: blue (2 squares), mint (2 squares), rose (3 squares), khaki (7 squares), slate (11 squares), orange (11 squares), sea green (11 squares), teal (12 squares), pale yellow (16 squares), indigo (19 squares), red (23 squares), amber (27 squares). An even split would hand every color 12 squares, so the blue region is running 10 squares under that average while the amber region is the roomiest area on the grid with 27 squares.
That imbalance is the first thing to read, because every region takes exactly one queen regardless of how much space it owns. Blue has only 2 places to put its queen; amber has 27. The spread between them on this board is 25 squares, and the wider that spread runs, the more it pays to solve from the small end inward.
Look at arrangement as well as area. Blue is the densest region on this grid at 100% of a 2×1 frame; teal is the loosest, occupying only 48% of its 5×5 frame. The loose one reaches into more rows and columns, which is exactly why it usually settles last.
Region by region
Below is every color on #298 with its exact reach, smallest region first. It is worth a slow read: the spans reveal which rows and columns several regions are fighting over.
Blue covers 2 squares, spanning 2 rows and 1 column (rows 3–4, columns 6–6). It sits wholly inside column 6, so its queen must be in that column.
Mint occupies 2 squares within rows 4–4, columns 7–8. It never leaves row 4, so its queen is locked to that row.
Rose: 3 squares across rows 12–12, columns 1–3. It never leaves row 12, so its queen is locked to that row.
Khaki covers 7 squares, spanning 3 rows and 3 columns (rows 8–10, columns 1–3).
Slate occupies 11 squares within rows 4–7, columns 1–5.
Orange: 11 squares across rows 9–12, columns 9–12.
Sea green covers 11 squares, spanning 3 rows and 6 columns (rows 10–12, columns 1–6).
Teal occupies 12 squares within rows 8–12, columns 7–11.
Pale yellow: 16 squares across rows 1–9, columns 10–12.
Indigo covers 19 squares, spanning 4 rows and 6 columns (rows 1–4, columns 1–6).
Red occupies 23 squares within rows 5–11, columns 2–7.
Amber: 27 squares across rows 1–8, columns 7–11.
Where to start on this board
Blue is the natural opening on #298: it is the smallest region on the grid at 2 squares, boxed into rows 3–4 and columns 6–6. Since one of those squares must hold a queen, that block of 2 rows and 1 column is the most contested part of the board.
Because blue stays inside column 6, its queen belongs to that column and no other region may use it. Cross out the rest of column 6 straight away. Any color that was relying on those squares now has a visibly smaller footprint, and that shrinkage is where your second deduction comes from.
Work outward to the other flat regions next. Mint and rose 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 #298
A quick way to find the next move is to count how many different colors touch each line. On this board, rows 1 and 2 are the narrowest, touched by only 3 colors. Column 12 is the tightest column, with 2 colors.
The fewer colors a line touches, the sooner it surrenders its queen. A row meeting just 3 colors has to be claimed by one of them, which pushes every remaining region into the other 11 rows. Row 4, meeting 6 colors, is the opposite case — the busiest line on #298 and the last one you should expect to crack.
Working through the middle game
The middle of #298 is where careless play costs time. Every queen you place kills a row, a column and the eight surrounding squares; if you do not mark all of that immediately, you will later "discover" a move that was available several turns ago. Mark first, then look.
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.
Say the reason out loud: "this region has one square left", "this column has one square left". If no such sentence is available, the eliminating is not finished. One more pass of X marks is almost always quicker than committing to a placement you cannot defend.
Why puzzle #298 is rated easy
What earns a board its rating is the shape of its opening. Here that opening offers three single-line regions, a 2-square smallest color, a tightest row touched by 3 colors, and a region-size spread of 25. Lopsided grids with flat regions fall quickly; balanced ones like this take more patience.
Rating is a measure of chain length, not of chance. With one guaranteed solution and no guessing required, the only thing that changes across the collection is how many eliminations you must link together before a queen is provably forced.
If #298 feels harder than its rating suggests, the usual culprit is incomplete marking rather than a difficult deduction. Check that every queen already on the grid has its full cross of eliminations recorded — including the diagonal neighbours, which are by far the easiest to miss. More stalled solves come from one forgotten diagonal X than from any genuinely deep chain of logic.
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.
One pattern is worth learning at every size, and it is available here. When two regions can only fit inside the same two rows, they must take one row each — which locks every other region out of both. The same argument works for columns, and for any matching count: three regions sharing three rows, four sharing four. Spotting these pairings turns a slow grind into a quick cascade, and on #298 the place to look for one is around column 12.
Here is a shape check that gives nothing away: when #298 is solved, 4 queens sit on the outer edge of the grid and 8 sit inside it, and no queen lands in a corner. A work-in-progress board that clusters its queens in one quadrant while leaving others bare is usually carrying a mistake.
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 #298?
Puzzle #298 is rated easy. Its smallest color region holds 2 squares, its tightest row is touched by 3 colors, and three of its regions are confined to a single row or column, which gives you a forced move early.
Does 12x12 puzzle #298 have only one solution?
Yes. Every puzzle in the 12x12 collection, including #298, 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 #298?
Start with the blue region — the most constrained color on this board, with 2 squares spanning rows 3–4 and columns 6–6. Narrowing the smallest region first removes the most squares elsewhere on the grid.