aoc-2021-rust

Advent of Code 2021 Solutions in Rust
git clone https://git.sinitax.com/sinitax/aoc-2021-rust
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part2 (1812B)


      1--- Part Two ---
      2
      3Based on your calculations, the planned course doesn't seem to make any sense. You find the
      4submarine manual and discover that the process is actually slightly more complicated.
      5
      6In addition to horizontal position and depth, you'll also need to track a third value,
      7aim, which also starts at 0. The commands also mean something entirely different than
      8you first thought:
      9
     10
     11 - down X increases your aim by X units.
     12
     13 - up X decreases your aim by X units.
     14
     15 - forward X does two things:
     16 - It increases your horizontal position by X units.
     17
     18 - It increases your depth by your aim multiplied by X.
     19
     20
     21
     22
     23Again note that since you're on a submarine, down and up do the opposite of what you might expect:
     24"down" means aiming in the positive direction.
     25
     26Now, the above example does something different:
     27
     28
     29 - forward 5 adds 5 to your horizontal position, a total of 5. Because your aim is 0, your depth
     30does not change.
     31
     32 - down 5 adds 5 to your aim, resulting in a value of 5.
     33
     34 - forward 8 adds 8 to your horizontal position, a total of 13. Because your aim is 5, your depth
     35increases by 8*5=40.
     36
     37 - up 3 decreases your aim by 3, resulting in a value of 2.
     38
     39 - down 8 adds 8 to your aim, resulting in a value of 10.
     40
     41 - forward 2 adds 2 to your horizontal position, a total of 15.  Because your aim is 10, your depth
     42increases by 2*10=20 to a total of 60.
     43
     44
     45After following these new instructions, you would have a horizontal position of 15 and a depth of
     4660. (Multiplying these produces 900.)
     47
     48Using this new interpretation of the commands, calculate the horizontal position and depth you would
     49have after following the planned course. What do you get if you multiply your final
     50horizontal position by your final depth?
     51
     52