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day08: replace static foreach with workaround
author Jordi Gutiérrez Hermoso <>
date Tue, 16 Jan 2018 11:28:55 -0500
parents 049fb8e56025
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--- Day 8: I Heard You Like Registers ---

You receive a signal directly from the CPU. Because of your recent
assistance with jump instructions, it would like you to compute the
result of a series of unusual register instructions.

Each instruction consists of several parts: the register to modify,
whether to increase or decrease that register's value, the amount by
which to increase or decrease it, and a condition. If the condition
fails, skip the instruction without modifying the register. The
registers all start at 0. The instructions look like this:

b inc 5 if a > 1
a inc 1 if b < 5
c dec -10 if a >= 1
c inc -20 if c == 10

These instructions would be processed as follows:

    Because a starts at 0, it is not greater than 1, and so b is not

    a is increased by 1 (to 1) because b is less than 5 (it is 0).

    c is decreased by -10 (to 10) because a is now greater than or
    equal to 1 (it is 1).

    c is increased by -20 (to -10) because c is equal to 10.

After this process, the largest value in any register is 1.

You might also encounter <= (less than or equal to) or != (not equal
to). However, the CPU doesn't have the bandwidth to tell you what all
the registers are named, and leaves that to you to determine.

What is the largest value in any register after completing the
instructions in your puzzle input?

Your puzzle answer was 4902.

--- Part Two ---

To be safe, the CPU also needs to know the highest value held in any
register during this process so that it can decide how much memory to
allocate to these operations. For example, in the above instructions,
the highest value ever held was 10 (in register c after the third
instruction was evaluated).

Your puzzle answer was 7037.

Both parts of this puzzle are complete! They provide two gold stars: **