Advent of Functional PHP: Day 3

Submitted by Larry on 4 December 2021 - 6:15pm

The third challenge in this year's Advent of Code is all about bit manipulation. We're asked to read in a series of binary numbers and interpret them in various entirely illogical ways as a form of diagnostics. (Incidentally, if you ever write a system that requires this kind of logic to debug its output, you're fired.)

In any case, we're given a file with a list of 12 digit binary numbers and asked to compute various values. In the first part, we are asked to find the most common bit (0 or 1) in each position, and the result is known as "gamma." Then we have to find the least common bit in each position, and the result is known as "epsilon." (I don't know why you would want to do this; it's all Greek to me.)

In practice, the functional part of the solution isn't all that challenging. It was the bit-wise manipulation that was tricky, as I rarely do bitwise operations. But we do get to show off a few new functional tracks, so let's dig in.

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