Are these hard bridges puzzles free to print?

Yes. Generate the puzzle above and print it with its answer, at no cost and with no sign-up.

Does every puzzle have one solution?

Yes. Every bridge beyond the first network is tried against a solver and kept only while the board still joins up one way, because adding one blindly usually gives the numbers somewhere else to be satisfied. The answer is on the second page.

Can I make a bridges book to sell on KDP?

Yes. The free tool makes one puzzle. The KDP bridges maker generates hundreds of graded puzzles at any KDP trim, as a print-ready 300 DPI interior and solutions PDF.

Free printable

Hard bridges

A hard bridges puzzle is an eleven by eleven board carrying eighteen islands. At this size the numbers alone will not finish it: the move that does is noticing a group of islands that has quietly satisfied itself and cut itself off from the rest.

Difficulty

More islands is what makes a board harder, not a bigger grid. A wide board with few islands gives the numbers almost nothing to choose between, so the grades add islands and grow the board to fit them.

11×11 board, 18 islands. Join the islands with bridges along the rows and columns so each holds exactly its number of bridge ends, no two bridges cross, at most two join any pair, and every island ends up in one connected network.

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Bridges Hard

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Bridges Hard · Solution

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How to solve a bridges puzzle

Join the numbered islands with bridges running along the rows and columns, so that each island holds exactly its number of bridge ends, no two bridges cross, at most two join any pair, and every island ends up in one connected network.

The method

1Start with the islands that have no choice. Count an island’s neighbours and work out the most bridges it could possibly take: two to each. An island marked 4 with only two neighbours must send two each way. A 6 with three neighbours is the same. Those are free, and they usually open a corner.
2Use the almost-full islands next. An island marked 3 with two neighbours must send at least one bridge each way, because two to one side would leave three for the other and three is not allowed. The same reasoning gives a 5 with three neighbours one bridge in every direction. You are not placing the whole number, just the part of it that cannot go anywhere else.
3Watch what each bridge rules out. Every bridge you draw blocks the line it crosses, so a bridge between two islands can make a crossing bridge impossible and force its island to look elsewhere. That is usually where the next deduction comes from rather than from the numbers themselves.
4Never close off a group. If a handful of islands have all their numbers satisfied and no bridge joins them to the rest, the whole arrangement is wrong, because every island has to end up in one network. Checking for that as you go saves you from a board that looks finished and is not.

The one rule people get wrong: Bridges never cross, and they never pass over an island either. A line from one island to another two places away is only legal if nothing at all sits between them.
What the answer page shows: The same islands with every bridge drawn in, single or double, so you can check a pair at a glance.
How the grades differ: More islands, on a bigger board to fit them. The island count is what makes a board hard: a wide board with few islands gives the numbers almost nothing to choose between.
Is it the same as a nonogram?: No, though both work from numbers at the edge of a shape. A nonogram has you shade squares from run lengths; here you draw lines between places, and the rule that no two cross is what gives the puzzle its character.
Good for: Anyone who likes a puzzle that is drawn rather than filled in.

Making a whole bridges book?

This page makes one puzzle. To publish a book on Amazon KDP, the KDP bridges maker generates hundreds of graded puzzles at any trim, as a print-ready 300 DPI interior and solutions PDF.

More printable bridges puzzles

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Questions

Are these hard bridges puzzles free to print?: Yes. Generate the puzzle above and print it with its answer, at no cost and with no sign-up.
Does every puzzle have one solution?: Yes. Every bridge beyond the first network is tried against a solver and kept only while the board still joins up one way, because adding one blindly usually gives the numbers somewhere else to be satisfied. The answer is on the second page.
Can I make a bridges book to sell on KDP?: Yes. The free tool makes one puzzle. The KDP bridges maker generates hundreds of graded puzzles at any KDP trim, as a print-ready 300 DPI interior and solutions PDF.