66 lines
2.5 KiB
Markdown
66 lines
2.5 KiB
Markdown
# Day 1: Trebuchet?!
|
|
|
|
## Part 1
|
|
|
|
Something is wrong with global snow production, and you've been selected to take a look.
|
|
The Elves have even given you a map; on it, they've used stars to mark the top fifty
|
|
locations that are likely to be having problems.
|
|
|
|
You've been doing this long enough to know that to restore snow operations, you need to
|
|
check all *fifty stars* by December 25th.
|
|
|
|
Collect stars by solving puzzles. Two puzzles will be made available on each day in
|
|
the Advent calendar; the second puzzle is unlocked when you complete the first. Each
|
|
puzzle grants *one star*. Good luck!
|
|
|
|
You try to ask why they can't just use a weather machine ("not powerful enough") and where
|
|
they're even sending you ("the sky") and why your map looks mostly blank ("you sure ask a
|
|
lot of questions") and hang on did you just say the sky ("of course, where do you think
|
|
snow comes from") when you realize that the Elves are already loading you into a
|
|
trebuchet ("please hold still, we need to strap you in").
|
|
|
|
As they're making the final adjustments, they discover that their calibration
|
|
document (your puzzle input) has been **amended** by a very young Elf who was apparently
|
|
just excited to show off her art skills. Consequently, the Elves are having trouble
|
|
reading the values on the document.
|
|
|
|
The newly-improved calibration document consists of lines of text; each line originally
|
|
contained a specific **calibration value** that the Elves now need to recover. On each line,
|
|
the calibration value can be found by combining the **first digit** and the **last digit**
|
|
(in that order) to form a single **two-digit number**.
|
|
|
|
For example:
|
|
|
|
```
|
|
1abc2
|
|
pqr3stu8vwx
|
|
a1b2c3d4e5f
|
|
treb7uchet
|
|
```
|
|
|
|
In this example, the calibration values of these four lines are 12, 38, 15, and 77.
|
|
Adding these together produces 142.
|
|
|
|
Consider your entire calibration document. **What is the sum of all of the calibration values?**
|
|
|
|
## Part 2
|
|
|
|
Your calculation isn't quite right. It looks like some of the digits are actually spelled out
|
|
with letters: one, two, three, four, five, six, seven, eight, and nine also count as valid "digits".
|
|
|
|
Equipped with this new information, you now need to find the real first and last digit on each line. For example:
|
|
|
|
```
|
|
two1nine
|
|
eightwothree
|
|
abcone2threexyz
|
|
xtwone3four
|
|
4nineeightseven2
|
|
zoneight234
|
|
7pqrstsixteen
|
|
```
|
|
|
|
In this example, the calibration values are 29, 83, 13, 24, 42, 14, and 76. Adding these together produces *281*.
|
|
|
|
**What is the sum of all of the calibration values?**
|