diff --git a/5/2/input b/5/2/input new file mode 100644 index 0000000..c9a3512 --- /dev/null +++ b/5/2/input @@ -0,0 +1,174 @@ +seeds: 194657215 187012821 1093203236 6077151 44187305 148722449 2959577030 152281079 3400626717 198691716 1333399202 287624830 2657325069 35258407 1913289352 410917164 1005856673 850939 839895010 162018909 + +seed-to-soil map: +466206721 134904099 264145987 +3226739510 2500159633 122177414 +1107118949 4139510909 155456387 +2314679916 2622337047 59899451 +2642618541 1908002826 511067679 +0 399050086 167531444 +1262575336 2682236498 1052104580 +3448620320 1415756771 259155097 +302435543 566581530 163771178 +3348916924 4039807513 99703396 +3153686220 1674911868 73053290 +3788293662 1747965158 160037668 +3948331330 3734341078 305466435 +2374579367 1228806725 186950046 +2561529413 2419070505 81089128 +167531444 0 134904099 +3707775417 1148288480 80518245 +4253797765 1107118949 41169531 + +soil-to-fertilizer map: +3913658055 3217667557 44136240 +3043638173 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176268846 +3431278062 1484221851 471209429 +1981628291 3733754901 42054178 +4140073117 2681749584 154894179 +1484221851 4170138658 124828638 +3902487491 1955431280 237585626 +457604064 555138795 376843506 +3036948483 3775809079 394329579 +2920793607 2193016906 116154876 + +temperature-to-humidity map: +1348484361 0 45849582 +1394333943 726347262 166590764 +1797084784 3346946555 119105515 +1163891565 1265639794 165909682 +2199751891 3274125222 72821333 +4012454029 2231107899 181228118 +1008425725 207338839 56688993 +2322219090 3174539335 24543729 +3987057737 3199083064 25396292 +1560924707 45849582 62712410 +3424140824 1837299459 190417072 +2272573224 3224479356 27702302 +2346762819 2412336017 518856401 +329181964 1432789749 172164254 +3783666369 2027716531 203391368 +753484930 471406467 254940795 +1916190299 2931192418 243346917 +501346218 892938026 44760077 +1329801247 1604954003 18683114 +2865619220 3567337219 558521604 +546106295 264027832 207378635 +2300275526 3252181658 21943564 +4193682147 3466052070 101285149 +327941691 1431549476 1240273 +0 937698103 327941691 +2159537216 1797084784 40214675 +3614557896 4125858823 169108473 +1065114718 108561992 98776847 + +humidity-to-location map: +440744287 1133551978 536306564 +4042633851 4000620330 37465866 +977050851 1669858542 136276424 +2136551597 4038086196 256881100 +198620952 0 242123335 +1113327275 242123335 891428643 +4080099717 3802748040 197872290 +2695699324 2136551597 1346934527 +4277972007 3785752751 16995289 +2393432697 3483486124 302266627 +0 1806134966 198620952 diff --git a/5/2/puzzle.md b/5/2/puzzle.md new file mode 100644 index 0000000..49091f0 --- /dev/null +++ b/5/2/puzzle.md @@ -0,0 +1,139 @@ +\--- Day 5: If You Give A Seed A Fertilizer --- +---------- + +You take the boat and find the gardener right where you were told he would be: managing a giant "garden" that looks more to you like a farm. + +"A water source? Island Island *is* the water source!" You point out that Snow Island isn't receiving any water. + +"Oh, we had to stop the water because we *ran out of sand* to [filter](https://en.wikipedia.org/wiki/Sand_filter) it with! Can't make snow with dirty water. Don't worry, I'm sure we'll get more sand soon; we only turned off the water a few days... weeks... oh no." His face sinks into a look of horrified realization. + +"I've been so busy making sure everyone here has food that I completely forgot to check why we stopped getting more sand! There's a ferry leaving soon that is headed over in that direction - it's much faster than your boat. Could you please go check it out?" + +You barely have time to agree to this request when he brings up another. "While you wait for the ferry, maybe you can help us with our *food production problem*. The latest Island Island [Almanac](https://en.wikipedia.org/wiki/Almanac) just arrived and we're having trouble making sense of it." + +The almanac (your puzzle input) lists all of the seeds that need to be planted. It also lists what type of soil to use with each kind of seed, what type of fertilizer to use with each kind of soil, what type of water to use with each kind of fertilizer, and so on. Every type of seed, soil, fertilizer and so on is identified with a number, but numbers are reused by each category - that is, soil `123` and fertilizer `123` aren't necessarily related to each other. + +For example: + +``` +seeds: 79 14 55 13 + +seed-to-soil map: +50 98 2 +52 50 48 + +soil-to-fertilizer map: +0 15 37 +37 52 2 +39 0 15 + +fertilizer-to-water map: +49 53 8 +0 11 42 +42 0 7 +57 7 4 + +water-to-light map: +88 18 7 +18 25 70 + +light-to-temperature map: +45 77 23 +81 45 19 +68 64 13 + +temperature-to-humidity map: +0 69 1 +1 0 69 + +humidity-to-location map: +60 56 37 +56 93 4 + +``` + +The almanac starts by listing which seeds need to be planted: seeds `79`, `14`, `55`, and `13`. + +The rest of the almanac contains a list of *maps* which describe how to convert numbers from a *source category* into numbers in a *destination category*. That is, the section that starts with `seed-to-soil map:` describes how to convert a *seed number* (the source) to a *soil number* (the destination). This lets the gardener and his team know which soil to use with which seeds, which water to use with which fertilizer, and so on. + +Rather than list every source number and its corresponding destination number one by one, the maps describe entire *ranges* of numbers that can be converted. Each line within a map contains three numbers: the *destination range start*, the *source range start*, and the *range length*. + +Consider again the example `seed-to-soil map`: + +``` +50 98 2 +52 50 48 + +``` + +The first line has a *destination range start* of `50`, a *source range start* of `98`, and a *range length* of `2`. This line means that the source range starts at `98` and contains two values: `98` and `99`. The destination range is the same length, but it starts at `50`, so its two values are `50` and `51`. With this information, you know that seed number `98` corresponds to soil number `50` and that seed number `99` corresponds to soil number `51`. + +The second line means that the source range starts at `50` and contains `48` values: `50`, `51`, ..., `96`, `97`. This corresponds to a destination range starting at `52` and also containing `48` values: `52`, `53`, ..., `98`, `99`. So, seed number `53` corresponds to soil number `55`. + +Any source numbers that *aren't mapped* correspond to the *same* destination number. So, seed number `10` corresponds to soil number `10`. + +So, the entire list of seed numbers and their corresponding soil numbers looks like this: + +``` +seed soil +0 0 +1 1 +... ... +48 48 +49 49 +50 52 +51 53 +... ... +96 98 +97 99 +98 50 +99 51 + +``` + +With this map, you can look up the soil number required for each initial seed number: + +* Seed number `79` corresponds to soil number `81`. +* Seed number `14` corresponds to soil number `14`. +* Seed number `55` corresponds to soil number `57`. +* Seed number `13` corresponds to soil number `13`. + +The gardener and his team want to get started as soon as possible, so they'd like to know the closest location that needs a seed. Using these maps, find *the lowest location number that corresponds to any of the initial seeds*. To do this, you'll need to convert each seed number through other categories until you can find its corresponding *location number*. In this example, the corresponding types are: + +* Seed `79`, soil `81`, fertilizer `81`, water `81`, light `74`, temperature `78`, humidity `78`, *location `82`*. +* Seed `14`, soil `14`, fertilizer `53`, water `49`, light `42`, temperature `42`, humidity `43`, *location `43`*. +* Seed `55`, soil `57`, fertilizer `57`, water `53`, light `46`, temperature `82`, humidity `82`, *location `86`*. +* Seed `13`, soil `13`, fertilizer `52`, water `41`, light `34`, temperature `34`, humidity `35`, *location `35`*. + +So, the lowest location number in this example is `*35*`. + +*What is the lowest location number that corresponds to any of the initial seed numbers?* + +Your puzzle answer was `157211394`. + +The first half of this puzzle is complete! It provides one gold star: \* + +\--- Part Two --- +---------- + +Everyone will starve if you only plant such a small number of seeds. Re-reading the almanac, it looks like the `seeds:` line actually describes *ranges of seed numbers*. + +The values on the initial `seeds:` line come in pairs. Within each pair, the first value is the *start* of the range and the second value is the *length* of the range. So, in the first line of the example above: + +``` +seeds: 79 14 55 13 +``` + +This line describes two ranges of seed numbers to be planted in the garden. The first range starts with seed number `79` and contains `14` values: `79`, `80`, ..., `91`, `92`. The second range starts with seed number `55` and contains `13` values: `55`, `56`, ..., `66`, `67`. + +Now, rather than considering four seed numbers, you need to consider a total of *27* seed numbers. + +In the above example, the lowest location number can be obtained from seed number `82`, which corresponds to soil `84`, fertilizer `84`, water `84`, light `77`, temperature `45`, humidity `46`, and *location `46`*. So, the lowest location number is `*46*`. + +Consider all of the initial seed numbers listed in the ranges on the first line of the almanac. *What is the lowest location number that corresponds to any of the initial seed numbers?* + +Answer: + +Although it hasn't changed, you can still [get your puzzle input](5/input). + +You can also [Shareon [Twitter](https://twitter.com/intent/tweet?text=I%27ve+completed+Part+One+of+%22If+You+Give+A+Seed+A+Fertilizer%22+%2D+Day+5+%2D+Advent+of+Code+2023&url=https%3A%2F%2Fadventofcode%2Ecom%2F2023%2Fday%2F5&related=ericwastl&hashtags=AdventOfCode) [Mastodon](javascript:void(0);)] this puzzle. \ No newline at end of file diff --git a/5/2/solution.sh b/5/2/solution.sh new file mode 100755 index 0000000..0cddff4 --- /dev/null +++ b/5/2/solution.sh @@ -0,0 +1,95 @@ +#!/usr/bin/env bash + +set -o errexit +set -o nounset +set -o pipefail +if [[ "${TRACE-0}" == "1" ]]; then + set -o xtrace +fi + +cd "$(dirname "$0")" + +INPUT_FILE="$1" + +get_seed_pairs () +{ + IFS=" " read -r -a seeds <<< "$(grep seeds "${INPUT_FILE}" | cut -d ' ' -f 2-)" + seed_count="${#seeds[@]}" + pairs=$((seed_count/2)) + for ((i=0; i "${map_name}.map" + maps+=("${map_name}.map") +} + +map_seed () +{ + # Usage: map_seed MAP_FILE SEED_NUMBER + # Prints the mapping of the seed number in the give map. + local map seed dest_start source_start length diff + map="$1" + seed="$2" + while read -r line; do + dest_start=$(cut -d ' ' -f 1 <<< "${line}") + source_start=$(cut -d ' ' -f 2 <<< "${line}") + length=$(cut -d ' ' -f 3 <<< "${line}") + if [[ ${seed} -ge ${source_start} && ${seed} -le $((source_start+length-1)) ]]; then + diff=$((seed-source_start)) + echo -n $((dest_start+diff)) + return + fi + done < "${map}" + echo -n "${seed}" # no mapping +} + +main () +{ + declare -A seed_pairs=() + declare -a maps=() + local map_count destination lowest length seed + get_seed_pairs + map_count=$(awk -v RS= 'END {print NR}' "${INPUT_FILE}") + map_count=$((map_count-1)) # one of the paragraphs in the file is seeds + for ((i=1; i<=map_count; i++)); do + gen_map "${i}" + done + lowest='' + for s in "${!seed_pairs[@]}"; do + length=${seed_pairs[${s}]} + echo "running from start ${s} length ${length}" + for ((z=0; z