From 5f70c0666cb37d2cc19aca84b49435cf78650ef0 Mon Sep 17 00:00:00 2001
From: Lars Martens <lars@martens.red>
Date: Tue, 5 Dec 2023 12:08:13 +0100
Subject: [PATCH] Solve day 5 part 1

---
 input/05-test |  33 +++++++++++++
 src/bin/05.rs | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 159 insertions(+)
 create mode 100644 input/05-test
 create mode 100644 src/bin/05.rs

diff --git a/input/05-test b/input/05-test
new file mode 100644
index 0000000..bd902a4
--- /dev/null
+++ b/input/05-test
@@ -0,0 +1,33 @@
+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
\ No newline at end of file
diff --git a/src/bin/05.rs b/src/bin/05.rs
new file mode 100644
index 0000000..65506f5
--- /dev/null
+++ b/src/bin/05.rs
@@ -0,0 +1,126 @@
+use itertools::Itertools;
+
+const INPUT: &str = include_str!("../../input/05");
+const TEST_INPUT: &str = include_str!("../../input/05-test");
+
+fn main() {
+    assert_eq!(part1(TEST_INPUT), 35);
+    println!("Part 1: {}", part1(INPUT));
+    assert_eq!(part2(TEST_INPUT), 46);
+    println!("Part 2: {}", part2(INPUT));
+}
+
+fn part1(input: &str) -> u64 {
+    let garden = Garden::parse(input);
+    garden
+        .simple_seeds
+        .iter()
+        .copied()
+        .map(|seed| garden.map(seed))
+        .min()
+        .unwrap()
+}
+
+fn part2(input: &str) -> u64 {
+    0
+}
+
+#[derive(Debug)]
+struct Garden {
+    simple_seeds: Vec<u64>,
+    seed_ranges: Vec<SeedRange>,
+    maps: Vec<Map>,
+}
+
+impl Garden {
+    fn parse(input: &str) -> Self {
+        let mut blocks = input.split("\n\n");
+        let seeds = blocks.next().unwrap().strip_prefix("seeds: ").unwrap();
+        let maps = blocks.map(Map::parse).collect();
+
+        let simple_seeds = parse_ws_numbers(seeds);
+        let seed_ranges = simple_seeds
+            .iter()
+            .copied()
+            .tuples()
+            .map(|(start, length)| SeedRange { start, length })
+            .collect();
+
+        Self {
+            simple_seeds,
+            seed_ranges,
+            maps,
+        }
+    }
+
+    /// Look up n in every map.
+    fn map(&self, mut n: u64) -> u64 {
+        for map in &self.maps {
+            n = map.map(n);
+        }
+        n
+    }
+}
+
+#[derive(Debug)]
+struct SeedRange {
+    start: u64,
+    length: u64,
+}
+
+#[derive(Debug)]
+struct Map {
+    ranges: Vec<MappedRange>,
+}
+
+impl Map {
+    fn map(&self, n: u64) -> u64 {
+        for range in &self.ranges {
+            if let Some(mapped) = range.map(n) {
+                return mapped;
+            }
+        }
+
+        n
+    }
+
+    fn parse(block: &str) -> Self {
+        let lines = block.lines().skip(1);
+        let ranges = lines.map(MappedRange::parse).collect();
+        Self { ranges }
+    }
+}
+
+#[derive(Debug)]
+struct MappedRange {
+    destination: u64,
+    source: u64,
+    length: u64,
+}
+
+impl MappedRange {
+    fn map(&self, n: u64) -> Option<u64> {
+        let source_start = self.source;
+        let source_end = source_start + self.length;
+        if (source_start..source_end).contains(&n) {
+            Some(n - source_start + self.destination)
+        } else {
+            None
+        }
+    }
+
+    fn parse(line: &str) -> Self {
+        let [destination, source, length] = parse_ws_numbers(line).try_into().unwrap();
+        Self {
+            destination,
+            source,
+            length,
+        }
+    }
+}
+
+fn parse_ws_numbers(s: &str) -> Vec<u64> {
+    s.split_ascii_whitespace()
+        .map(|s| s.parse().unwrap())
+        .collect()
+}