131 lines
5.3 KiB
Plaintext
131 lines
5.3 KiB
Plaintext
Advent of Code
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br0xen [7](AoC++) 6*
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--- Day 3: Lobby ---
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You descend a short staircase, enter the surprisingly vast lobby, and are
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quickly cleared by the security checkpoint. When you get to the main
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elevators, however, you discover that each one has a red light above it:
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they're all offline.
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"Sorry about that," an Elf apologizes as she tinkers with a nearby control
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panel. "Some kind of electrical surge seems to have fried them. I'll try
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to get them online soon."
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You explain your need to get further underground. "Well, you could at
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least take the escalator down to the printing department, not that you'd
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get much further than that without the elevators working. That is, you
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could if the escalator weren't also offline."
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"But, don't worry! It's not fried; it just needs power. Maybe you can get
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it running while I keep working on the elevators."
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There are batteries nearby that can supply emergency power to the
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escalator for just such an occasion. The batteries are each labeled with
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their [16]joltage rating, a value from 1 to 9. You make a note of their
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joltage ratings (your puzzle input). For example:
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987654321111111
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811111111111119
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234234234234278
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818181911112111
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The batteries are arranged into banks; each line of digits in your input
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corresponds to a single bank of batteries. Within each bank, you need to
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turn on exactly two batteries; the joltage that the bank produces is equal
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to the number formed by the digits on the batteries you've turned on. For
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example, if you have a bank like 12345 and you turn on batteries 2 and 4,
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the bank would produce 24 jolts. (You cannot rearrange batteries.)
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You'll need to find the largest possible joltage each bank can produce. In
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the above example:
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• In 987654321111111, you can make the largest joltage possible, 98, by
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turning on the first two batteries.
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• In 811111111111119, you can make the largest joltage possible by
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turning on the batteries labeled 8 and 9, producing 89 jolts.
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• In 234234234234278, you can make 78 by turning on the last two
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batteries (marked 7 and 8).
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• In 818181911112111, the largest joltage you can produce is 92.
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The total output joltage is the sum of the maximum joltage from each bank,
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so in this example, the total output joltage is 98 + 89 + 78 + 92 = 357.
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There are many batteries in front of you. Find the maximum joltage
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possible from each bank; what is the total output joltage?
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Your puzzle answer was 17113.
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--- Part Two ---
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The escalator doesn't move. The Elf explains that it probably needs more
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joltage to overcome the [17]static friction of the system and hits the big
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red "joltage limit safety override" button. You lose count of the number
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of times she needs to confirm "yes, I'm sure" and decorate the lobby a bit
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while you wait.
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Now, you need to make the largest joltage by turning on exactly twelve
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batteries within each bank.
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The joltage output for the bank is still the number formed by the digits
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of the batteries you've turned on; the only difference is that now there
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will be 12 digits in each bank's joltage output instead of two.
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Consider again the example from before:
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987654321111111
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811111111111119
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234234234234278
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818181911112111
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Now, the joltages are much larger:
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• In 987654321111111, the largest joltage can be found by turning on
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everything except some 1s at the end to produce 987654321111.
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• In the digit sequence 811111111111119, the largest joltage can be
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found by turning on everything except some 1s, producing 811111111119.
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• In 234234234234278, the largest joltage can be found by turning on
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everything except a 2 battery, a 3 battery, and another 2 battery near
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the start to produce 434234234278.
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• In 818181911112111, the joltage 888911112111 is produced by turning on
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everything except some 1s near the front.
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The total output joltage is now much larger: 987654321111 + 811111111119 +
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434234234278 + 888911112111 = 3121910778619.
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What is the new total output joltage?
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Your puzzle answer was 169709990062889.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should [18]return to your Advent calendar and try
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another puzzle.
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If you still want to see it, you can [19]get your puzzle input.
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References
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Visible links
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1. https://adventofcode.com/
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2. https://adventofcode.com/2025/about
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3. https://adventofcode.com/2025/events
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5. https://adventofcode.com/2025/settings
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6. https://adventofcode.com/2025/auth/logout
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7. Advent of Code Supporter
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https://adventofcode.com/2025/support
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8. https://adventofcode.com/2025
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9. https://adventofcode.com/2025
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10. https://adventofcode.com/2025/support
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11. https://adventofcode.com/2025/sponsors
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12. https://adventofcode.com/2025/leaderboard/private
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13. https://adventofcode.com/2025/stats
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14. https://adventofcode.com/2025/sponsors
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15. https://adventofcode.com/2025/sponsors/redirect?url=https%3A%2F%2Ffullscript%2Ecom%2Fcareers
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16. https://adventofcode.com/2020/day/10
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17. https://en.wikipedia.org/wiki/Static_friction
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18. https://adventofcode.com/2025
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19. https://adventofcode.com/2025/day/3/input
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22. javascript:void(0);
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