A campsite with strict rules
Tents and Trees is a grid puzzle where the trees are given and you pitch the tents. Each tree gets exactly one tent beside it, above, below, left or right. Tents never touch, not even at a corner. The numbers on the edges say how many tents each row and column holds. Those three rules interact tightly, and most squares can be ruled out long before you know where a tent goes.
Clearing the field first
The quickest progress comes from deciding where tents cannot go. Grass is your note for that, and on this board you can drag to spread it.
- Zero lines. A row or column numbered 0 holds no tents. Tap its number once it is green and the board grasses the rest for you.
- Squares far from trees. A tent must sit right beside a tree. Any square that does not touch a tree on one of its four sides can never hold a tent, so grass it.
On a fresh 9×9 board, these three sweeps often grass half the field before you place a single tent. What remains is a much smaller puzzle.
Placing tents with confidence
With the field cleared, compare each line's number with the squares still open in it.
- Exact fit. If a row needs two tents and only two open squares remain, and they do not touch, both are tents.
- Lonely trees. If a tree has only one open square beside it, that square is its tent.
- After every tent. Grass all eight squares around a new tent. Then check whether its row and column are now full; if so, tap the number to grass the rest.
Here is a worked example on the 7×7 Easy board. Say a row needs exactly one tent, and after clearing, only two open squares remain in it, side by side. You cannot tell which one is the tent yet. But a tent in either square would touch the squares directly above and below both of them. Any square in the rows above and below that touches both candidates is ruled out either way, so grass those. That small step often leaves a nearby tree with a single option, and the row settles itself on the next pass.
The pairing rule people forget
The count rule and the no-touching rule are easy to see on the board. The pairing rule is quieter. Every tent must belong to its own tree, and every tree to its own tent.
- Two trees, one square. If two trees share a single open square between them, only one of them can use it. The other must find its tent elsewhere.
- Too many tents near one tree. A tent that touches two trees still only counts for one. Make sure the other tree has its own.
- Count trees, not just numbers. The total of the row numbers always equals the number of trees. When you are stuck, count the trees in a region and compare with the tents its lines allow.
Habits that prevent errors
- Pitching on a count alone. A row needing one tent does not tell you where. Wait until the column or a tree narrows it down.
- Skipping the corners of a tent. Diagonal touching is still touching. After placing a tent, grass all eight surrounding squares, not just four.
- Ignoring red numbers. A number turns red when its line has too many tents. Undo rather than shuffling tents around by hand.
How the three sizes build skill
Easy is 7×7 with seven pairs, so the clearing sweeps and lonely-tree rule usually finish it. Medium is 9×9 with twelve pairs, where the side-by-side trick from the example begins to matter. Hard is 11×11 with eighteen pairs, and here the pairing rule does real work, since crowded clusters of trees share squares between them.
Every puzzle has exactly one solution. The hint first removes a tent that does not belong, then pitches one the solution needs. Use it to check your thinking rather than to move forward, and try to explain each hinted tent before you continue. Like Nonograms at /games/nonograms, this puzzle rewards checking each line's number against what is left in it.
