Binary Puzzle
How to solve a binary puzzle (Takuzu): four moves, no guessing
Updated Tuesday, October 27
To solve a binary puzzle, look for two identical symbols side by side and close them in with the other symbol, fill the gap between two alike, and count: once a line has its share of 0s, the rest are 1s. Every Gridarium binary puzzle can be finished this way, without guessing.
The rules
Fill every square with a 0 or a 1. Never three identical symbols side by side or one above another. Every row and every column holds as many 0s as 1s. No two rows are the same, and no two columns are the same.
Step 1: close in a pair
Two 0s side by side? The squares at each end must be 1s, or there would be three 0s in a row. The same goes for two 1s, across or down.
Step 2: fill the gap
0, empty, 0: the middle square must be a 1. Same for 1, empty, 1.
Step 3: count the line
A line of eight squares holds four 0s and four 1s. As soon as a line has four 0s, every empty square in it is a 1.
Step 4: rule out what the line cannot hold
When a line is nearly full, try each way to finish it in your head: a choice that would make three in a row somewhere else, or break the count, is impossible. Bigger puzzles need this.
Step 5: no copies
If a line could still end up identical to a line that is already full, the squares that would make it a copy must take the other symbol. Hard puzzles use this.
The three levels
- Easy: 6 by 6.
- Medium: 8 by 8.
- Hard: 10 by 10.