What is Hashi?
Hashi is a map of islands, each with a number. You draw bridges between them, straight across in a row or a column, until every island has as many bridges as its number says. Two islands can share one bridge or two, bridges can’t cross, and when you’re done every island must be joined into one network.
The full name is Hashiwokakero, Japanese for “build bridges!”. Nikoli first published it in 1990, and it’s also sold as Bridges, Chopsticks and Ai-Ki-Ai.
How to start a Hashi
Look for islands with few neighbours and big numbers. An island can share at most two bridges with each neighbour, so a 4 in a corner with two neighbours needs a double bridge to both. A 3 in the same spot needs at least one bridge to each.
Next, use the rule that everything joins up. Two 1s can never be joined to each other, and two 2s can’t share a double bridge, because either would make a little group that can’t reach anyone else.
As islands fill up, their neighbours lose options. Keep counting: what each island still needs, and how much its remaining neighbours could still give.
Common mistakes
It’s easy to finish every number and still have two separate groups. The puzzle isn’t solved until the whole map is one network, and the bridges turn red to tell you.
Bridges can’t bend, and they can’t jump over an island to reach one further away.
Questions
- What does Hashiwokakero mean?
- It’s Japanese for “build bridges!”. Hashi means bridge, and the shorter name is what most players use.
- Can more than two bridges join two islands?
- No. Each pair of islands shares no bridge, one bridge or two.
- Can bridges cross?
- No. Bridges that cross turn red on the board.
- Does every Hashi have one solution?
- Yes. Each one is checked by a solver that counts every possible answer, and it’s solved step by step without guessing before it’s published.
- How big are the puzzles?
- The daily Hashi is 10×10, picked as the hardest of 40 candidates. Practice puzzles come in 7×7, 9×9 and 12×12.