# Archipelago

In the Pacific, a small but friendly tribe inhabits a series of islands. Travelling between the islands is perilous due to maneating sharks and strong undercurrents. The tribe's shaman has decreed that bridges connecting all islands must be built to ensure safe passage.

In this puzzle a number of islands have to be connected to eachother with straight bridges. In exactly one way all islands can be connected such that every piece of bridge drawn is functional. Bridges do not cross and are only horizontal or vertical.

## Example

We will solve a small example puzzle.

In the puzzle to the left we have an archipelago of five islands. The key to solve this small diagram is in considering the island on the right. The large island to the left is the only island to which a road could lead from there, because above, below and to the right there is nothing.

The road we will draw now, limits the possibilities for filling in the rest of the puzzle considerably. For the small island on top the only choice left is to connect it to larger island. The other two roads follow logically in the same way.

Note that sometimes it can be helpful to use the fact that the puzzle has exactly one solution: Three of the roads in the example puzzle can not be crossed by any other road in the diagram, which means they can be drawn without much further thought. Why? Suppose they would not be part of the final solution, then we could draw them in later on and have an extra solution, but that is in contradiction with the fact that there is only one solution!

## Background

This genre was invented by Maarten Löffler.

Puzzles in this genre.
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