78 lines
3.0 KiB
Plaintext
78 lines
3.0 KiB
Plaintext
Advent of Code
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--- Day 5: A Maze of Twisty Trampolines, All Alike ---
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An urgent interrupt arrives from the CPU: it's trapped in a maze of jump instructions, and it would
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like assistance from any programs with spare cycles to help find the exit.
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The message includes a list of the offsets for each jump. Jumps are relative: -1 moves to the
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previous instruction, and 2 skips the next one. Start at the first instruction in the list. The goal
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is to follow the jumps until one leads outside the list.
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In addition, these instructions are a little strange; after each jump, the offset of that
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instruction increases by 1. So, if you come across an offset of 3, you would move three instructions
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forward, but change it to a 4 for the next time it is encountered.
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For example, consider the following list of jump offsets:
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0
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3
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0
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1
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-3
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Positive jumps ("forward") move downward; negative jumps move upward. For legibility in this
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example, these offset values will be written all on one line, with the current instruction marked in
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parentheses. The following steps would be taken before an exit is found:
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* (0) 3 0 1 -3 - before we have taken any steps.
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* (1) 3 0 1 -3 - jump with offset 0 (that is, don't jump at all). Fortunately, the instruction
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is then incremented to 1.
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* 2 (3) 0 1 -3 - step forward because of the instruction we just modified. The first
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instruction is incremented again, now to 2.
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* 2 4 0 1 (-3) - jump all the way to the end; leave a 4 behind.
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* 2 (4) 0 1 -2 - go back to where we just were; increment -3 to -2.
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* 2 5 0 1 -2 - jump 4 steps forward, escaping the maze.
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In this example, the exit is reached in 5 steps.
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How many steps does it take to reach the exit?
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Your puzzle answer was 343364.
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--- Part Two ---
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Now, the jumps are even stranger: after each jump, if the offset was three or more, instead decrease
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it by 1. Otherwise, increase it by 1 as before.
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Using this rule with the above example, the process now takes 10 steps, and the offset values after
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finding the exit are left as 2 3 2 3 -1.
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How many steps does it now take to reach the exit?
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Your puzzle answer was 25071947.
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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 return to your advent calendar and try another puzzle.
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If you still want to see it, you can get your puzzle input.
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References
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Visible links
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. http://adventofcode.com/
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. http://adventofcode.com/2017
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. http://adventofcode.com/2017/day/5/input
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