day5 solution 1

1 files changed, 118 insertions, 0 deletions

diff --git a/src/bin/day5.rs b/src/bin/day5.rs
new file mode 100644
index 0000000..c8456dd
--- /dev/null
+++ b/src/bin/day5.rs
@@ -0,0 +1,118 @@
+static DAY: u8 = 5;
+
+fn main() {
+    let input = advent::read_lines(DAY);
+    println!("{DAY}a: {}", lowest_location(&input));
+    println!("{DAY}b: {}", 0);
+}
+
+#[derive(Clone, Copy)]
+struct RangeMap {
+    dst_start: u64,
+    src_start: u64,
+    range: u64,
+}
+
+impl RangeMap {
+    fn new(input: &str) -> RangeMap {
+        let values = input.split(' ')
+                          .map(|x| x.parse().unwrap())
+                          .collect::<Vec<_>>();
+
+        RangeMap { dst_start: values[0], src_start: values[1], range: values[2] }
+    }
+}
+
+struct RangeCategory {
+    ranges: Vec<RangeMap>,
+}
+
+impl RangeCategory {
+    fn map(&self, val: u64) -> u64 {
+        for range in &self.ranges {
+            if range.src_start <= val && val < range.src_start + range.range {
+                return range.dst_start + val - range.src_start
+            }
+        }
+        val
+    }
+}
+
+fn lowest_location(input: &[String]) -> u64 {
+    let (_, seeds_str) = input[0].split_once(": ").unwrap();
+    let seeds = seeds_str.split(' ')
+                         .map(|x| x.parse().unwrap())
+                         .collect::<Vec<u64>>();
+
+    let mut range_maps = Vec::new();
+    let mut current_category = Vec::new();
+    for line in input.iter().skip(2) {
+        if line.is_empty() {
+            range_maps.push(RangeCategory { ranges: current_category.clone() });
+            current_category.clear();
+            continue;
+        }
+        if !line.chars().next().unwrap().is_ascii_digit() {
+            /* new category */
+            continue;
+        }
+        current_category.push(RangeMap::new(line));
+    }
+    range_maps.push(RangeCategory { ranges: current_category.clone() });
+
+    let mut locations = Vec::new();
+    for seed in seeds {
+        let mut next_val = seed;
+        for category in &range_maps {
+            next_val = category.map(next_val);
+        }
+        locations.push(next_val);
+    }
+
+    *locations.iter().min().unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = [
+            "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"
+        ].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
+        assert_eq!(lowest_location(&input), 35);
+    }
+}