Spaces:
Running
Running
| --- Day 4: Ceres Search --- | |
| "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! | |
| 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. | |
| 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 .: | |
| ..X... | |
| .SAMX. | |
| .A..A. | |
| XMAS.S | |
| .X.... | |
| The actual word search will be full of letters instead. For example: | |
| MMMSXXMASM | |
| MSAMXMSMSA | |
| AMXSXMAAMM | |
| MSAMASMSMX | |
| XMASAMXAMM | |
| XXAMMXXAMA | |
| SMSMSASXSS | |
| SAXAMASAAA | |
| MAMMMXMMMM | |
| MXMXAXMASX | |
| 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 .: | |
| ....XXMAS. | |
| .SAMXMS... | |
| ...S..A... | |
| ..A.A.MS.X | |
| XMASAMX.MM | |
| X.....XA.A | |
| S.S.S.S.SS | |
| .A.A.A.A.A | |
| ..M.M.M.MM | |
| .X.X.XMASX | |
| Take a look at the little Elf's word search. How many times does XMAS appear? | |
| --- Part Two --- | |
| The Elf looks quizzically at you. Did you misunderstand the assignment? | |
| 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: | |
| M.S | |
| .A. | |
| M.S | |
| Irrelevant characters have again been replaced with . in the above diagram. Within the X, each MAS can be written forwards or backwards. | |
| Here's the same example from before, but this time all of the X-MASes have been kept instead: | |
| .M.S...... | |
| ..A..MSMS. | |
| .M.S.MAA.. | |
| ..A.ASMSM. | |
| .M.S.M.... | |
| .......... | |
| S.S.S.S.S. | |
| .A.A.A.A.. | |
| M.M.M.M.M. | |
| .......... | |
| In this example, an X-MAS appears 9 times. | |
| 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? | |