Nichole Mattera
f0dee6e1d9

1 year ago  

..  
README.md  1 year ago  
input  1 year ago  
main.go  1 year ago 
README.md
Day 2: Dive!
Now, you need to figure out how to pilot this thing.
It seems like the submarine can take a series of commands like forward 1
, down 2
, or up 3
:
forward X
increases the horizontal position byX
units.down X
increases the depth byX
units.up X
decreases the depth byX
units.
Note that since you're on a submarine, down
and up
affect your depth, and so they have the opposite result of what you might expect.
The submarine seems to already have a planned course (your puzzle input). You should probably figure out where it's going. For example:
forward 5
down 5
forward 8
up 3
down 8
forward 2
Your horizontal position and depth both start at 0. The steps above would then modify them as follows:
forward 5
adds5
to your horizontal position, a total of5
.down 5
adds5
to your depth, resulting in a value of5
.forward 8
adds8
to your horizontal position, a total of13
.up 3
decreases your depth by3
, resulting in a value of2
.down 8
adds8
to your depth, resulting in a value of10
.forward 2
adds2
to your horizontal position, a total of15
.
After following these instructions, you would have a horizontal position of 15
and a depth of 10
. (Multiplying these together produces 150
.)
Calculate the horizontal position and depth you would have after following the planned course. What do you get if you multiply your final horizontal position by your final depth?
Part Two
Based on your calculations, the planned course doesn't seem to make any sense. You find the submarine manual and discover that the process is actually slightly more complicated.
In addition to horizontal position and depth, you'll also need to track a third value, aim, which also starts at 0
. The commands also mean something entirely different than you first thought:
down X
increases your aim byX
units.up X
decreases your aim byX
units.forward X
does two things: It increases your horizontal position by
X
units.  It increases your depth by your aim multiplied by
X
.
 It increases your horizontal position by
Again note that since you're on a submarine, down
and up
do the opposite of what you might expect: "down" means aiming in the positive direction.
Now, the above example does something different:
forward 5
adds5
to your horizontal position, a total of5
. Because your aim is0
, your depth does not change.down 5
adds5
to your aim, resulting in a value of5
.forward 8
adds8
to your horizontal position, a total of13
. Because your aim is5
, your depth increases by8*5=40
.up 3
decreases your aim by3
, resulting in a value of2
.down 8
adds8
to your aim, resulting in a value of10
.forward 2
adds2
to your horizontal position, a total of15
. Because your aim is10
, your depth increases by2*10=20
to a total of60
.
After following these new instructions, you would have a horizontal position of 15
and a depth of 60
. (Multiplying these produces 900
.)
Using this new interpretation of the commands, calculate the horizontal position and depth you would have after following the planned course. What do you get if you multiply your final horizontal position by your final depth?