1 files changed, 195 insertions, 0 deletions
diff --git a/src/day_05.rs b/src/day_05.rs
new file mode 100644
index 0000000..e9d0b92
--- /dev/null
+++ b/src/day_05.rs
@@ -0,0 +1,195 @@
+use std::{ops::Range, str::FromStr};
+
+use crate::{Problem, Solution};
+
+pub struct Day05;
+
+impl Problem for Day05 {
+    const DAY: u8 = 5;
+
+    const INPUT: &'static str = include_str!("../input/day_05.txt");
+}
+
+impl Solution for Day05 {
+    type Answer1 = usize;
+
+    type Answer2 = usize;
+
+    fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
+        let (first, rest) = input
+            .trim()
+            .split_once('\n')
+            .ok_or(anyhow::format_err!("Missing value map label"))?;
+
+        let mut values = first
+            .strip_prefix("seeds: ")
+            .ok_or(anyhow::format_err!("Failed to get seeds"))?
+            .split_whitespace()
+            .map(FromStr::from_str)
+            .try_collect::<Vec<usize>>()?;
+
+        let value_maps = rest
+            .trim()
+            .split("\n\n")
+            .map(parse_value_maps)
+            .try_collect::<Vec<_>>()?;
+
+        for value_map in value_maps {
+            values.iter_mut().for_each(|value| {
+                if let Some(v) = value_map.iter().find_map(|v| v.map_value(*value)) {
+                    *value = v
+                }
+            })
+        }
+
+        values
+            .into_iter()
+            .min()
+            .ok_or(anyhow::format_err!("No values found"))
+    }
+
+    fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
+        let (first, rest) = input
+            .trim()
+            .split_once('\n')
+            .ok_or(anyhow::format_err!("Missing value map label"))?;
+
+        let seeds: Vec<Range<usize>> = first
+            .strip_prefix("seeds: ")
+            .ok_or(anyhow::format_err!("Failed to get seeds"))?
+            .split_whitespace()
+            .map(FromStr::from_str)
+            .try_collect::<Vec<usize>>()?
+            .into_iter()
+            .array_chunks()
+            .map(|[n, len]| Range {
+                start: n,
+                end: n + len,
+            })
+            .collect();
+
+        let max = seeds
+            .iter()
+            .map(|r| r.end)
+            .max()
+            .ok_or(anyhow::format_err!("Failed to get max seed"))?;
+
+        let value_maps = rest
+            .trim()
+            .split("\n\n")
+            .map(parse_value_maps)
+            .try_collect::<Vec<_>>()?;
+
+        (0..=max)
+            .find(|location| {
+                let mut value = *location;
+                for value_map in value_maps.iter().rev() {
+                    if let Some(v) = value_map.iter().find_map(|v| v.r_map_value(value)) {
+                        value = v;
+                    }
+                }
+                seeds.iter().any(|s| s.contains(&value))
+            })
+            .ok_or(anyhow::format_err!("Failed to find min seed"))
+    }
+}
+
+fn parse_value_maps(s: &str) -> anyhow::Result<Vec<ValueMap>> {
+    s.trim()
+        .lines()
+        .skip(1)
+        .map(FromStr::from_str)
+        .try_collect::<Vec<ValueMap>>()
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+struct ValueMap {
+    source: Range<usize>,
+    destination: Range<usize>,
+    offset: isize,
+}
+
+impl ValueMap {
+    fn map_value(&self, value: usize) -> Option<usize> {
+        self.source
+            .contains(&value)
+            .then_some((value as isize + self.offset) as usize)
+    }
+
+    fn r_map_value(&self, value: usize) -> Option<usize> {
+        self.destination
+            .contains(&value)
+            .then_some((value as isize - self.offset) as usize)
+    }
+}
+
+impl FromStr for ValueMap {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut iter = s.trim().splitn(3, ' ').map(FromStr::from_str);
+
+        let (Some(Ok(destination_start)), Some(Ok(source_start)), Some(Ok(length))) =
+            (iter.next(), iter.next(), iter.next())
+        else {
+            anyhow::bail!("Invalid value map range");
+        };
+
+        Ok(Self {
+            source: source_start..source_start + length,
+            destination: destination_start..destination_start + length,
+            offset: isize::try_from(destination_start)? - isize::try_from(source_start)?,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = indoc::indoc! {"
+        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
+    "};
+
+    #[test]
+    fn test_part_1() -> anyhow::Result<()> {
+        Ok(assert_eq!(35, Day05::part_1(INPUT)?))
+    }
+
+    #[test]
+    fn test_part_2() -> anyhow::Result<()> {
+        Ok(assert_eq!(46, Day05::part_2(INPUT)?))
+    }
+}