94 lines
2.5 KiB
Markdown
94 lines
2.5 KiB
Markdown
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"Looks like the Chief's not here. Next!" One of The Historians pulls out a device and pushes the only button on it. After a brief flash, you recognize the interior of the [Ceres monitoring station](/2019/day/10)!
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As the search for the Chief continues, a small Elf who lives on the station tugs on your shirt; she'd like to know if you could help her with her *word search* (your puzzle input). She only has to find one word: `XMAS`.
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This word search allows words to be horizontal, vertical, diagonal, written backwards, or even overlapping other words. It's a little unusual, though, as you don't merely need to find one instance of `XMAS` - you need to find *all of them*. Here are a few ways `XMAS` might appear, where irrelevant characters have been replaced with `.`:
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```
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..X...
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.SAMX.
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.A..A.
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XMAS.S
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.X....
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```
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The actual word search will be full of letters instead. For example:
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```
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MMMSXXMASM
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MSAMXMSMSA
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AMXSXMAAMM
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MSAMASMSMX
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XMASAMXAMM
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XXAMMXXAMA
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SMSMSASXSS
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SAXAMASAAA
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MAMMMXMMMM
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MXMXAXMASX
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```
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In this word search, `XMAS` occurs a total of `*18*` times; here's the same word search again, but where letters not involved in any `XMAS` have been replaced with `.`:
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```
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....XXMAS.
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.SAMXMS...
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...S..A...
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..A.A.MS.X
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XMASAMX.MM
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X.....XA.A
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S.S.S.S.SS
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.A.A.A.A.A
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..M.M.M.MM
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.X.X.XMASX
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```
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Take a look at the little Elf's word search. *How many times does `XMAS` appear?*
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Your puzzle answer was `2530`.
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\--- Part Two ---
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----------
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The Elf looks quizzically at you. Did you misunderstand the assignment?
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Looking for the instructions, you flip over the word search to find that this isn't actually an `*XMAS*` puzzle; it's an `*X-MAS*` puzzle in which you're supposed to find two `MAS` in the shape of an `X`. One way to achieve that is like this:
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```
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M.S
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.A.
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M.S
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```
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Irrelevant characters have again been replaced with `.` in the above diagram. Within the `X`, each `MAS` can be written forwards or backwards.
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Here's the same example from before, but this time all of the `X-MAS`es have been kept instead:
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```
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.M.S......
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..A..MSMS.
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.M.S.MAA..
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..A.ASMSM.
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.M.S.M....
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..........
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S.S.S.S.S.
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.A.A.A.A..
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M.M.M.M.M.
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..........
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```
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In this example, an `X-MAS` appears `*9*` times.
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Flip the word search from the instructions back over to the word search side and try again. *How many times does an `X-MAS` appear?*
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Your puzzle answer was `1921`.
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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](/2024) and try another puzzle.
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If you still want to see it, you can [get your puzzle input](4/input).
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