From: Brett Parker Date: Wed, 15 Dec 2021 16:23:26 +0000 (+0000) Subject: Day 15 add description" X-Git-Url: https://git.sommitrealweird.co.uk/advent-of-code-2021.git/commitdiff_plain/8f18738f33eafb7a8d704bb8d7b762566453cd99 Day 15 add description" --- diff --git a/day15/task.txt b/day15/task.txt new file mode 100644 index 0000000..568a3f3 --- /dev/null +++ b/day15/task.txt @@ -0,0 +1,201 @@ +--- Day 15: Chiton --- + +You've almost reached the exit of the cave, but the walls are getting closer +together. Your submarine can barely still fit, though; the main problem is that +the walls of the cave are covered in chitons, and it would be best not to bump +any of them. + +The cavern is large, but has a very low ceiling, restricting your motion to two +dimensions. The shape of the cavern resembles a square; a quick scan of chiton +density produces a map of risk level throughout the cave (your puzzle input). +For example: + +1163751742 +1381373672 +2136511328 +3694931569 +7463417111 +1319128137 +1359912421 +3125421639 +1293138521 +2311944581 + +You start in the top left position, your destination is the bottom right +position, and you cannot move diagonally. The number at each position is its +risk level; to determine the total risk of an entire path, add up the risk +levels of each position you enter (that is, don't count the risk level of your +starting position unless you enter it; leaving it adds no risk to your total). + +Your goal is to find a path with the lowest total risk. In this example, a path +with the lowest total risk is highlighted here: + +1163751742 +1381373672 +2136511328 +3694931569 +7463417111 +1319128137 +1359912421 +3125421639 +1293138521 +2311944581 + +The total risk of this path is 40 (the starting position is never entered, so +its risk is not counted). + +What is the lowest total risk of any path from the top left to the bottom +right? + +Your puzzle answer was 393. + +--- Part Two --- + +Now that you know how to find low-risk paths in the cave, you can try to find +your way out. + +The entire cave is actually five times larger in both dimensions than you +thought; the area you originally scanned is just one tile in a 5x5 tile area +that forms the full map. Your original map tile repeats to the right and +downward; each time the tile repeats to the right or downward, all of its risk +levels are 1 higher than the tile immediately up or left of it. However, risk +levels above 9 wrap back around to 1. So, if your original map had some +position with a risk level of 8, then that same position on each of the 25 +total tiles would be as follows: + +8 9 1 2 3 +9 1 2 3 4 +1 2 3 4 5 +2 3 4 5 6 +3 4 5 6 7 + +Each single digit above corresponds to the example position with a value of 8 +on the top-left tile. Because the full map is actually five times larger in +both dimensions, that position appears a total of 25 times, once in each +duplicated tile, with the values shown above. + +Here is the full five-times-as-large version of the first example above, with +the original map in the top left corner highlighted: + +11637517422274862853338597396444961841755517295286 +13813736722492484783351359589446246169155735727126 +21365113283247622439435873354154698446526571955763 +36949315694715142671582625378269373648937148475914 +74634171118574528222968563933317967414442817852555 +13191281372421239248353234135946434524615754563572 +13599124212461123532357223464346833457545794456865 +31254216394236532741534764385264587549637569865174 +12931385212314249632342535174345364628545647573965 +23119445813422155692453326671356443778246755488935 +22748628533385973964449618417555172952866628316397 +24924847833513595894462461691557357271266846838237 +32476224394358733541546984465265719557637682166874 +47151426715826253782693736489371484759148259586125 +85745282229685639333179674144428178525553928963666 +24212392483532341359464345246157545635726865674683 +24611235323572234643468334575457944568656815567976 +42365327415347643852645875496375698651748671976285 +23142496323425351743453646285456475739656758684176 +34221556924533266713564437782467554889357866599146 +33859739644496184175551729528666283163977739427418 +35135958944624616915573572712668468382377957949348 +43587335415469844652657195576376821668748793277985 +58262537826937364893714847591482595861259361697236 +96856393331796741444281785255539289636664139174777 +35323413594643452461575456357268656746837976785794 +35722346434683345754579445686568155679767926678187 +53476438526458754963756986517486719762859782187396 +34253517434536462854564757396567586841767869795287 +45332667135644377824675548893578665991468977611257 +44961841755517295286662831639777394274188841538529 +46246169155735727126684683823779579493488168151459 +54698446526571955763768216687487932779859814388196 +69373648937148475914825958612593616972361472718347 +17967414442817852555392896366641391747775241285888 +46434524615754563572686567468379767857948187896815 +46833457545794456865681556797679266781878137789298 +64587549637569865174867197628597821873961893298417 +45364628545647573965675868417678697952878971816398 +56443778246755488935786659914689776112579188722368 +55172952866628316397773942741888415385299952649631 +57357271266846838237795794934881681514599279262561 +65719557637682166874879327798598143881961925499217 +71484759148259586125936169723614727183472583829458 +28178525553928963666413917477752412858886352396999 +57545635726865674683797678579481878968159298917926 +57944568656815567976792667818781377892989248891319 +75698651748671976285978218739618932984172914319528 +56475739656758684176786979528789718163989182927419 +67554889357866599146897761125791887223681299833479 + +Equipped with the full map, you can now find a path from the top left corner to +the bottom right corner with the lowest total risk: + +11637517422274862853338597396444961841755517295286 +13813736722492484783351359589446246169155735727126 +21365113283247622439435873354154698446526571955763 +36949315694715142671582625378269373648937148475914 +74634171118574528222968563933317967414442817852555 +13191281372421239248353234135946434524615754563572 +13599124212461123532357223464346833457545794456865 +31254216394236532741534764385264587549637569865174 +12931385212314249632342535174345364628545647573965 +23119445813422155692453326671356443778246755488935 +22748628533385973964449618417555172952866628316397 +24924847833513595894462461691557357271266846838237 +32476224394358733541546984465265719557637682166874 +47151426715826253782693736489371484759148259586125 +85745282229685639333179674144428178525553928963666 +24212392483532341359464345246157545635726865674683 +24611235323572234643468334575457944568656815567976 +42365327415347643852645875496375698651748671976285 +23142496323425351743453646285456475739656758684176 +34221556924533266713564437782467554889357866599146 +33859739644496184175551729528666283163977739427418 +35135958944624616915573572712668468382377957949348 +43587335415469844652657195576376821668748793277985 +58262537826937364893714847591482595861259361697236 +96856393331796741444281785255539289636664139174777 +35323413594643452461575456357268656746837976785794 +35722346434683345754579445686568155679767926678187 +53476438526458754963756986517486719762859782187396 +34253517434536462854564757396567586841767869795287 +45332667135644377824675548893578665991468977611257 +44961841755517295286662831639777394274188841538529 +46246169155735727126684683823779579493488168151459 +54698446526571955763768216687487932779859814388196 +69373648937148475914825958612593616972361472718347 +17967414442817852555392896366641391747775241285888 +46434524615754563572686567468379767857948187896815 +46833457545794456865681556797679266781878137789298 +64587549637569865174867197628597821873961893298417 +45364628545647573965675868417678697952878971816398 +56443778246755488935786659914689776112579188722368 +55172952866628316397773942741888415385299952649631 +57357271266846838237795794934881681514599279262561 +65719557637682166874879327798598143881961925499217 +71484759148259586125936169723614727183472583829458 +28178525553928963666413917477752412858886352396999 +57545635726865674683797678579481878968159298917926 +57944568656815567976792667818781377892989248891319 +75698651748671976285978218739618932984172914319528 +56475739656758684176786979528789718163989182927419 +67554889357866599146897761125791887223681299833479 + +The total risk of this path is 315 (the starting position is still never +entered, so its risk is not counted). + +Using the full map, what is the lowest total risk of any path from the top left +to the bottom right? + +Your puzzle answer was 2823. + +Both parts of this puzzle are complete! They provide two gold stars: ** + +At this point, you should return to your Advent calendar and try another +puzzle. + +If you still want to see it, you can get your puzzle input. + +You can also [Share] this puzzle. +