aoc2021/README.md

Advent of Code 2021

The 2021 iteration of Advent of Code. This year I am going to try and accomplish it all on my iPad using GitPod

Adding a new day

When starting to solve for a new day run the following command in the root of the repo where <day> is the go lang compatible package name (i.e. four or five) and <noun> represents the item the day's problem revolves around (i.e. radar or bingo).

./setup.sh <day> <noun>

After generating a new package update main.go to include a <day> flag in the switch statement on line 28

  case "<day>":
		day = <day>.Init("<day>/input.txt")

My Solutions

These solutions are based on my input values provided to me. The inputs I was provided are also included in this repo.

Day 1

$ ./aoc2021 --one
The solution for "one" is:
There were 1715 increases in depth
There were 1739 increases in depth when sampling a window

Day 2

$ ./aoc2021 --two
The solution for "two" is:
Horizontal is 1832, depth is 1172, answer is 2147104
Horizontal is 1832, depth is 1116059, answer is 2044620088

Day 3

$ ./aoc2021 --three
The solution for "three" is:
The power rates are gamma: 1143, epsilon: 2952, for 3374136 total
The oxygen rating is 1909 and CO2 rating is 2322, for a life support rating of 4432698

Day 4

$ ./aoc2021 --four
The solution for "four" is:
The winning score is 668 on call 66. Final score 44088
The last winning score is 263 on call 90. Final score 23670

Day five

$ ./aoc2021 --five
The solution for "five" is:
There are 5585 overlapping vents

There are 17193 overlapping vents

Day six

$ ./aoc2021 --six
The solution for "six" is:
After 80 days there are 377263 fish
After 256 days there are 1695929023803 fish

Day seven

$ ./aoc2021 --seven
The solution for "seven" is:
Used 357353 fuel to align
Used 104822130 fuel to align

Day eight

$ ./aoc2021 --eight
The solution for "eight" is:
There were 476 instances of digits 1, 4, 7, or 8
The sum of the decoded output values was 1011823

Day nine

$ ./aoc2021 --nine
The solution for "nine" is:
The sum of the risk level of low points is 439
The product of the three largest basins is 900900

Day ten

$ ./aoc2021 --ten
The solution for "ten" is:
The syntax error score is 323613
The autoComplete score is 3103006161

Day eleven

$ ./aoc2021 --eleven
The solution for "eleven" is:
There were 1669 flashes after 100 steps
They all flash on step 351

Day twelve

$ ./aoc2021 --twelve
The solution for "twelve" is:
Found 5157 paths through the cave system
Found 144309 paths through the cave system

Day thirteen

$ ./aoc2021 --thirteen
The solution for "thirteen" is:
There are 837 dots after 1 fold
#### ###  ####  ##  #  #  ##  #  # #  #
#    #  #    # #  # # #  #  # #  # #  #
###  #  #   #  #    ##   #    #### #  #
#    ###   #   # ## # #  #    #  # #  #
#    #    #    #  # # #  #  # #  # #  #
#### #    ####  ### #  #  ##  #  #  ##
This is the activation code

Day fourteen

$ ./aoc2021 --fourteen
The solution for "fourteen" is:
The result of subtracting the least from most common element quantities is 2988
The result of subtracting the least from most common element quantities is 3572761917024

Day fifteen

Today's solution is SLLLLLLOOOOOOOWWW (~75 minutes) but correct!

$ ./aoc2021 --fifteen
The solution for "fifteen" is:
The total risk of the least risky path is 415
The total risk of the least risky path is 2864

Day sixteen

$ ./aoc2021 --sixteen
The solution for "sixteen" is:
The sum of the version numbers is 1012
The output of the encoded input is 2223947372407

Day seventeen

$ ./aoc2021 --seventeen
The solution for "seventeen" is:
The max height is 35511
There are 3282 initial velocities that will hit the target

Day eighteen

$ ./aoc2021 --eighteen
The solution for "eighteen" is:
The magnitude of the final sum is 4202
The largest magnitude of any two snail numbers is 4779