Four Bits Square

0001
0001
0001
0001
In the 4x4 grid shown, the 4-bit binary patterns 0000, 0001, 1000, and 1111 can all be found in at least one of the 10 different lines (4 rows, 4 columns, 2 diagonals). Fill the grid with 1s and 0s to find as many 4-bit binary patterns as possible. As above, you may read in either direction to find the patterns.

Source: Original.


Solutions were received from Robert T McQuaid, Alexander Doskey, Philippe Fondanaiche, Carlos Rivera, Arturo Pascalin, Kirk Bresniker.

There are 10 basic solutions, each of which has 15 of the 16 possible 4-bit patterns. (A grid with all 16 is impossible.) Rotating, reflecting, or exchanging 1s with 0s will find the rest of the 160 possible solutions. Many thanks to Carlos Rivera for finding these 10 solutions.
0001
0101
1111
1001
0001
0110
1100
1101
0001
0111
1100
1001
0001
0111
1101
1001
0001
1010
0110
1011
0001
1010
0111
1001
0001
1010
1111
1001
0001
1011
0111
1001
0001
1111
0011
1001
0001
1111
1100
1001
As shown above it is not possible to have both 0000 and 1111 in a grid with 15 solutions.

Several solvers suggested a quick follow-up puzzle to find the grids in which only 2 unique 4-bit patterns can be found. (There are only 4.)


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