Campsite

Also known as:

Tents, Tents And Trees, Tree-dimensional

Campsite, also known as Tents or Tents And Trees, is a placement puzzle which first came to our attention in the Dutch magazine 'Brein Brekers', and appeals due to the interesting logic deriving from its small number of simple rules.

In a rectangular grid, a number of trees are placed; each tree has one tent 'tied' to it in a neighbouring square, and the number of tents to be placed in each row and column is also given. It should be noted, by the way, that a tent cannot be placed in the same square as a tree. The major rule which makes the puzzle solvable, however, is that no two tents can be in touching squares, even if they touch only at a corner – and it is this constraint which suggests some solving strategies to apply.

As with many puzzles of similar form, the methodical approach here is to use a process of elimination. It may be possible to conclude that a pair of neighbouring squares must contain one tent, even though it isn't yet known which one; however, up to four adjoining squares can be eliminated as a result, as they touch both. By similar logic, if a tent must go into a 1x3 region, then up to two adjoining squares can be eliminated.

Another line of attack, which helps somewhat in the sample puzzle here, is to tackle two adjacent rows as a whole, keeping in mind that a 2x2 box can contain at most one tent.

Campsite puzzles were a regular feature in 'Tough Puzzles' from 2004 to 2007.

Instructions


Each tree has exactly one tent tied to it, which is in a horizontally or vertically neighbouring square. Also, no two tents are in adjacent squares, not even diagonally. The numbers outside the grid show how many tents are in each row or column. Can you deduce where the tents are placed

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