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๐ - 2025 DAY 10 SOLUTIONS - ๐
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Solution Threads
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console.log('Hello World')
In this case, I formulated both questions as a linear algebra question. The first one is over the finite field F2, which I solved by using the library galois and some manual row reduction. The second was over positive integers which is not a field, so I solved it over Q using sympy and then looked for positive integer minimal solutions. In some cases these are under determined, and in some cases exactly solvable systems of the form Ax = b for x where A is the vector made from button switch vectors, b is the light switch pattern vector in the first case or jolts in the second. For under determined ones, your solutions are of the form particular + linear combinations of null space (mod 2 in the first case) so you only search for the minimal one there and in the second you have to search both minimal and positive integer one (because your solution will be over Q and not Z+) in the second case. Wonders of vectorization makes a quick work of these last parts (0.2 second in the first problem about 20s in the second). Also nullspace seems to generally have less than or equal to two dimensions so search space is much smaller than using all the button press vectors.