When we were in Paris in April (yes, April in Paris!), I read Le Figaro every day to catch up on the election news (Sarkozy vs. Hollande vs. Le Pen) and to help try improve my French comprehension. While the latter was fairly successful, I was diverted by the puzzles page. Not only was there a Sudoku puzzle, but there was another puzzle I hadn’t seen before called Takuzu.
It’s a fill-in-the-grid logic puzzle, but unlike Sudoku you can only use 0s and 1s. Here’s an example from binarypuzzle.com, tagged as “easy”:
There are some rules to follow too:
It’s quite fun to do. Let’s take a look at solving this one. I generally start off by blocking off the runs of two 0s or 1s (applying rule 2).
As you can see, this oftentimes produces more runs of two, so you can apply rule 2 recursively.
Take a look at row 5 now. Notice that it already has four 1s. By an application of rule 1 you can fill in the remaining two cells with 0s. Column 4 is even simpler to complete using the same rule. However take a look at row 3 for an example of applying some lateral thinking. In that row, there are two copies of the following pattern:
1 <empty> 1. Consider putting a 1 in the empty cell: you’d end up with three 1s in a row, a violation of rule 2. So, that empty cell can only be a 0. In this example there are several examples of this pattern (don’t forget the columns as well).
And this, of course, gives more opportunities to apply the first couple of rules. And, in this case, we can finish the puzzle quite quickly.
As this is an easy puzzle, we didn’t have to use rule 3. Generally, it’s only the more difficult puzzles that rely on this particular rule.
If you want to practice, I’d pop on over to binarypuzzle.com and try a few out. The hard ones require a bit more lateral thinking than I’ve shown here.
If you have an iPhone, there are also several apps available in the AppStore that implement the game. Unfortunately the name Takuzu is not widely known (it seems to be limited to France and Le Figaro especially, and sounds like a Japanese weed to me) so you have to search for “binary puzzle” or even “binary Sudoku puzzle”. Here are a few:
Anyway, have fun!