refactored project structure

story/story01a.txt

@@ -0,0 +1,60 @@
+--- Day 1: Secret Entrance ---
+
+The Elves have good news and bad news.
+
+The good news is that they've discovered project management! This has given them the tools they need to prevent their usual Christmas emergency. For example, they now know that the North Pole decorations need to be finished soon so that other critical tasks can start on time.
+
+The bad news is that they've realized they have a different emergency: according to their resource planning, none of them have any time left to decorate the North Pole!
+
+To save Christmas, the Elves need you to finish decorating the North Pole by December 12th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on each day; the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!
+
+You arrive at the secret entrance to the North Pole base ready to start decorating. Unfortunately, the password seems to have been changed, so you can't get in. A document taped to the wall helpfully explains:
+
+"Due to new security protocols, the password is locked in the safe below. Please see the attached document for the new combination."
+
+The safe has a dial with only an arrow on it; around the dial are the numbers 0 through 99 in order. As you turn the dial, it makes a small click noise as it reaches each number.
+
+The attached document (your puzzle input) contains a sequence of rotations, one per line, which tell you how to open the safe. A rotation starts with an L or R which indicates whether the rotation should be to the left (toward lower numbers) or to the right (toward higher numbers). Then, the rotation has a distance value which indicates how many clicks the dial should be rotated in that direction.
+
+So, if the dial were pointing at 11, a rotation of R8 would cause the dial to point at 19. After that, a rotation of L19 would cause it to point at 0.
+
+Because the dial is a circle, turning the dial left from 0 one click makes it point at 99. Similarly, turning the dial right from 99 one click makes it point at 0.
+
+So, if the dial were pointing at 5, a rotation of L10 would cause it to point at 95. After that, a rotation of R5 could cause it to point at 0.
+
+The dial starts by pointing at 50.
+
+You could follow the instructions, but your recent required official North Pole secret entrance security training seminar taught you that the safe is actually a decoy. The actual password is the number of times the dial is left pointing at 0 after any rotation in the sequence.
+
+For example, suppose the attached document contained the following rotations:
+
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82
+
+Following these rotations would cause the dial to move as follows:
+
+    The dial starts by pointing at 50.
+    The dial is rotated L68 to point at 82.
+    The dial is rotated L30 to point at 52.
+    The dial is rotated R48 to point at 0.
+    The dial is rotated L5 to point at 95.
+    The dial is rotated R60 to point at 55.
+    The dial is rotated L55 to point at 0.
+    The dial is rotated L1 to point at 99.
+    The dial is rotated L99 to point at 0.
+    The dial is rotated R14 to point at 14.
+    The dial is rotated L82 to point at 32.
+
+Because the dial points at 0 a total of three times during this process, the password in this example is 3.
+
+Analyze the rotations in your attached document. What's the actual password to open the door?

story/story01b.txt

@@ -0,0 +1,29 @@
+--- Part Two ---
+
+You're sure that's the right password, but the door won't open. You knock, but nobody answers. You build a snowman while you think.
+
+As you're rolling the snowballs for your snowman, you find another security document that must have fallen into the snow:
+
+"Due to newer security protocols, please use password method 0x434C49434B until further notice."
+
+You remember from the training seminar that "method 0x434C49434B" means you're actually supposed to count the number of times any click causes the dial to point at 0, regardless of whether it happens during a rotation or at the end of one.
+
+Following the same rotations as in the above example, the dial points at zero a few extra times during its rotations:
+
+    The dial starts by pointing at 50.
+    The dial is rotated L68 to point at 82; during this rotation, it points at 0 once.
+    The dial is rotated L30 to point at 52.
+    The dial is rotated R48 to point at 0.
+    The dial is rotated L5 to point at 95.
+    The dial is rotated R60 to point at 55; during this rotation, it points at 0 once.
+    The dial is rotated L55 to point at 0.
+    The dial is rotated L1 to point at 99.
+    The dial is rotated L99 to point at 0.
+    The dial is rotated R14 to point at 14.
+    The dial is rotated L82 to point at 32; during this rotation, it points at 0 once.
+
+In this example, the dial points at 0 three times at the end of a rotation, plus three more times during a rotation. So, in this example, the new password would be 6.
+
+Be careful: if the dial were pointing at 50, a single rotation like R1000 would cause the dial to point at 0 ten times before returning back to 50!
+
+Using password method 0x434C49434B, what is the password to open the door?

story/story02a.txt

@@ -0,0 +1,37 @@
+--- Day 2: Gift Shop ---
+
+You get inside and take the elevator to its only other stop: the gift shop. "Thank you for visiting the North Pole!" gleefully exclaims a nearby sign. You aren't sure who is even allowed to visit the North Pole, but you know you can access the lobby through here, and from there you can access the rest of the North Pole base.
+
+As you make your way through the surprisingly extensive selection, one of the clerks recognizes you and asks for your help.
+
+As it turns out, one of the younger Elves was playing on a gift shop computer and managed to add a whole bunch of invalid product IDs to their gift shop database! Surely, it would be no trouble for you to identify the invalid product IDs for them, right?
+
+They've even checked most of the product ID ranges already; they only have a few product ID ranges (your puzzle input) that you'll need to check. For example:
+
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,
+1698522-1698528,446443-446449,38593856-38593862,565653-565659,
+824824821-824824827,2121212118-2121212124
+
+(The ID ranges are wrapped here for legibility; in your input, they appear on a single long line.)
+
+The ranges are separated by commas (,); each range gives its first ID and last ID separated by a dash (-).
+
+Since the young Elf was just doing silly patterns, you can find the invalid IDs by looking for any ID which is made only of some sequence of digits repeated twice. So, 55 (5 twice), 6464 (64 twice), and 123123 (123 twice) would all be invalid IDs.
+
+None of the numbers have leading zeroes; 0101 isn't an ID at all. (101 is a valid ID that you would ignore.)
+
+Your job is to find all of the invalid IDs that appear in the given ranges. In the above example:
+
+    11-22 has two invalid IDs, 11 and 22.
+    95-115 has one invalid ID, 99.
+    998-1012 has one invalid ID, 1010.
+    1188511880-1188511890 has one invalid ID, 1188511885.
+    222220-222224 has one invalid ID, 222222.
+    1698522-1698528 contains no invalid IDs.
+    446443-446449 has one invalid ID, 446446.
+    38593856-38593862 has one invalid ID, 38593859.
+    The rest of the ranges contain no invalid IDs.
+
+Adding up all the invalid IDs in this example produces 1227775554.
+
+What do you get if you add up all of the invalid IDs?

story/story02b.txt

@@ -0,0 +1,23 @@
+--- Part Two ---
+
+The clerk quickly discovers that there are still invalid IDs in the ranges in your list. Maybe the young Elf was doing other silly patterns as well?
+
+Now, an ID is invalid if it is made only of some sequence of digits repeated at least twice. So, 12341234 (1234 two times), 123123123 (123 three times), 1212121212 (12 five times), and 1111111 (1 seven times) are all invalid IDs.
+
+From the same example as before:
+
+    11-22 still has two invalid IDs, 11 and 22.
+    95-115 now has two invalid IDs, 99 and 111.
+    998-1012 now has two invalid IDs, 999 and 1010.
+    1188511880-1188511890 still has one invalid ID, 1188511885.
+    222220-222224 still has one invalid ID, 222222.
+    1698522-1698528 still contains no invalid IDs.
+    446443-446449 still has one invalid ID, 446446.
+    38593856-38593862 still has one invalid ID, 38593859.
+    565653-565659 now has one invalid ID, 565656.
+    824824821-824824827 now has one invalid ID, 824824824.
+    2121212118-2121212124 now has one invalid ID, 2121212121.
+
+Adding up all the invalid IDs in this example produces 4174379265.
+
+What do you get if you add up all of the invalid IDs using these new rules?

story/story03a.txt

@@ -0,0 +1,29 @@
+--- Day 3: Lobby ---
+
+You descend a short staircase, enter the surprisingly vast lobby, and are quickly cleared by the security checkpoint. When you get to the main elevators, however, you discover that each one has a red light above it: they're all offline.
+
+"Sorry about that," an Elf apologizes as she tinkers with a nearby control panel. "Some kind of electrical surge seems to have fried them. I'll try to get them online soon."
+
+You explain your need to get further underground. "Well, you could at least take the escalator down to the printing department, not that you'd get much further than that without the elevators working. That is, you could if the escalator weren't also offline."
+
+"But, don't worry! It's not fried; it just needs power. Maybe you can get it running while I keep working on the elevators."
+
+There are batteries nearby that can supply emergency power to the escalator for just such an occasion. The batteries are each labeled with their joltage rating, a value from 1 to 9. You make a note of their joltage ratings (your puzzle input). For example:
+
+987654321111111
+811111111111119
+234234234234278
+818181911112111
+
+The batteries are arranged into banks; each line of digits in your input corresponds to a single bank of batteries. Within each bank, you need to turn on exactly two batteries; the joltage that the bank produces is equal to the number formed by the digits on the batteries you've turned on. For example, if you have a bank like 12345 and you turn on batteries 2 and 4, the bank would produce 24 jolts. (You cannot rearrange batteries.)
+
+You'll need to find the largest possible joltage each bank can produce. In the above example:
+
+    In 987654321111111, you can make the largest joltage possible, 98, by turning on the first two batteries.
+    In 811111111111119, you can make the largest joltage possible by turning on the batteries labeled 8 and 9, producing 89 jolts.
+    In 234234234234278, you can make 78 by turning on the last two batteries (marked 7 and 8).
+    In 818181911112111, the largest joltage you can produce is 92.
+
+The total output joltage is the sum of the maximum joltage from each bank, so in this example, the total output joltage is 98 + 89 + 78 + 92 = 357.
+
+There are many batteries in front of you. Find the maximum joltage possible from each bank; what is the total output joltage?

story/story03b.txt

@@ -0,0 +1,25 @@
+--- Part Two ---
+
+The escalator doesn't move. The Elf explains that it probably needs more joltage to overcome the static friction of the system and hits the big red "joltage limit safety override" button. You lose count of the number of times she needs to confirm "yes, I'm sure" and decorate the lobby a bit while you wait.
+
+Now, you need to make the largest joltage by turning on exactly twelve batteries within each bank.
+
+The joltage output for the bank is still the number formed by the digits of the batteries you've turned on; the only difference is that now there will be 12 digits in each bank's joltage output instead of two.
+
+Consider again the example from before:
+
+987654321111111
+811111111111119
+234234234234278
+818181911112111
+
+Now, the joltages are much larger:
+
+    In 987654321111111, the largest joltage can be found by turning on everything except some 1s at the end to produce 987654321111.
+    In the digit sequence 811111111111119, the largest joltage can be found by turning on everything except some 1s, producing 811111111119.
+    In 234234234234278, the largest joltage can be found by turning on everything except a 2 battery, a 3 battery, and another 2 battery near the start to produce 434234234278.
+    In 818181911112111, the joltage 888911112111 is produced by turning on everything except some 1s near the front.
+
+The total output joltage is now much larger: 987654321111 + 811111111119 + 434234234278 + 888911112111 = 3121910778619.
+
+What is the new total output joltage?

story/story04a.txt

@@ -0,0 +1,41 @@
+--- Day 4: Printing Department ---
+
+You ride the escalator down to the printing department. They're clearly getting ready for Christmas; they have lots of large rolls of paper everywhere, and there's even a massive printer in the corner (to handle the really big print jobs).
+
+Decorating here will be easy: they can make their own decorations. What you really need is a way to get further into the North Pole base while the elevators are offline.
+
+"Actually, maybe we can help with that," one of the Elves replies when you ask for help. "We're pretty sure there's a cafeteria on the other side of the back wall. If we could break through the wall, you'd be able to keep moving. It's too bad all of our forklifts are so busy moving those big rolls of paper around."
+
+If you can optimize the work the forklifts are doing, maybe they would have time to spare to break through the wall.
+
+The rolls of paper (@) are arranged on a large grid; the Elves even have a helpful diagram (your puzzle input) indicating where everything is located.
+
+For example:
+
+..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.
+
+The forklifts can only access a roll of paper if there are fewer than four rolls of paper in the eight adjacent positions. If you can figure out which rolls of paper the forklifts can access, they'll spend less time looking and more time breaking down the wall to the cafeteria.
+
+In this example, there are 13 rolls of paper that can be accessed by a forklift (marked with x):
+
+..xx.xx@x.
+x@@.@.@.@@
+@@@@@.x.@@
+@.@@@@..@.
+x@.@@@@.@x
+.@@@@@@@.@
+.@.@.@.@@@
+x.@@@.@@@@
+.@@@@@@@@.
+x.x.@@@.x.
+
+Consider your complete diagram of the paper roll locations. How many rolls of paper can be accessed by a forklift?

story/story04b.txt

@@ -0,0 +1,131 @@
+--- Part Two ---
+
+Now, the Elves just need help accessing as much of the paper as they can.
+
+Once a roll of paper can be accessed by a forklift, it can be removed. Once a roll of paper is removed, the forklifts might be able to access more rolls of paper, which they might also be able to remove. How many total rolls of paper could the Elves remove if they keep repeating this process?
+
+Starting with the same example as above, here is one way you could remove as many rolls of paper as possible, using highlighted @ to indicate that a roll of paper is about to be removed, and using x to indicate that a roll of paper was just removed:
+
+Initial state:
+..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.
+
+Remove 13 rolls of paper:
+..xx.xx@x.
+x@@.@.@.@@
+@@@@@.x.@@
+@.@@@@..@.
+x@.@@@@.@x
+.@@@@@@@.@
+.@.@.@.@@@
+x.@@@.@@@@
+.@@@@@@@@.
+x.x.@@@.x.
+
+Remove 12 rolls of paper:
+.......x..
+.@@.x.x.@x
+x@@@@...@@
+x.@@@@..x.
+.@.@@@@.x.
+.x@@@@@@.x
+.x.@.@.@@@
+..@@@.@@@@
+.x@@@@@@@.
+....@@@...
+
+Remove 7 rolls of paper:
+..........
+.x@.....x.
+.@@@@...xx
+..@@@@....
+.x.@@@@...
+..@@@@@@..
+...@.@.@@x
+..@@@.@@@@
+..x@@@@@@.
+....@@@...
+
+Remove 5 rolls of paper:
+..........
+..x.......
+.x@@@.....
+..@@@@....
+...@@@@...
+..x@@@@@..
+...@.@.@@.
+..x@@.@@@x
+...@@@@@@.
+....@@@...
+
+Remove 2 rolls of paper:
+..........
+..........
+..x@@.....
+..@@@@....
+...@@@@...
+...@@@@@..
+...@.@.@@.
+...@@.@@@.
+...@@@@@x.
+....@@@...
+
+Remove 1 roll of paper:
+..........
+..........
+...@@.....
+..x@@@....
+...@@@@...
+...@@@@@..
+...@.@.@@.
+...@@.@@@.
+...@@@@@..
+....@@@...
+
+Remove 1 roll of paper:
+..........
+..........
+...x@.....
+...@@@....
+...@@@@...
+...@@@@@..
+...@.@.@@.
+...@@.@@@.
+...@@@@@..
+....@@@...
+
+Remove 1 roll of paper:
+..........
+..........
+....x.....
+...@@@....
+...@@@@...
+...@@@@@..
+...@.@.@@.
+...@@.@@@.
+...@@@@@..
+....@@@...
+
+Remove 1 roll of paper:
+..........
+..........
+..........
+...x@@....
+...@@@@...
+...@@@@@..
+...@.@.@@.
+...@@.@@@.
+...@@@@@..
+....@@@...
+
+Stop once no more rolls of paper are accessible by a forklift. In this example, a total of 43 rolls of paper can be removed.
+
+Start with your original diagram. How many rolls of paper in total can be removed by the Elves and their forklifts?