RiiR day 5

day05.rs

@@ -0,0 +1,77 @@
+use std::collections::HashSet;
+use std::io::{self, BufRead};
+
+fn parse_map(lines: &mut std::str::Lines<'_>) -> Vec<(u64, u64, u64)> {
+    let mut map = Vec::new();
+
+    loop {
+        let line = lines.next();
+        if line.is_none() {
+            break map;
+        }
+
+        let line = line.unwrap();
+        if line.is_empty() {
+            lines.next();
+            break map;
+        }
+
+        let mut tokens = line
+            .split_ascii_whitespace()
+            .map(|n| n.parse::<u64>().unwrap());
+        let numbers = (
+            tokens.next().unwrap(),
+            tokens.next().unwrap(),
+            tokens.next().unwrap(),
+        );
+        map.push(numbers);
+    }
+}
+
+fn transform_ranges(map: &[(u64, u64, u64)], ranges: &[(u64, u64)]) -> Vec<(u64, u64)> {
+    let mut output_ranges = Vec::new();
+    for (start, length) in ranges {
+        let (dst_start, src_start, len) = map
+            .iter()
+            .find(|(dst, src, len)| src <= start && *start < (src + len))
+            .unwrap_or(&(0u64, 0u64, u64::MAX));
+
+        let end = start + length;
+        let src_end = src_start + len;
+
+        output_ranges.push((dst_start + start - src_start, u64::min(src_end, end) - start));
+        if end > src_end {
+            output_ranges.extend(transform_ranges(map, &[(src_end, end - src_end)]));
+        }
+    }
+    output_ranges
+}
+
+fn do_the_thing(maps: &Vec<Vec<(u64, u64, u64)>>, mut ranges: Vec<(u64, u64)>) -> u64 {
+    for map in maps {
+        ranges = transform_ranges(&map, &ranges);
+    }
+    ranges.iter().min().unwrap().0
+}
+
+fn main() -> io::Result<()> {
+    let mut lines = include_str!("day05.in").lines();
+
+    let line = lines.next().unwrap();
+    let (_, seeds) = line.trim().split_once(": ").unwrap();
+    let seeds: Vec<u64> = seeds
+        .split_ascii_whitespace()
+        .map(|n| n.parse().unwrap())
+        .collect();
+
+    lines.next();
+    lines.next();
+
+    let maps: Vec<Vec<_>> = (0..7).map(|_| parse_map(&mut lines)).collect();
+
+    let part1 = do_the_thing(&maps, seeds.iter().map(|&seed| (seed, 1)).collect());
+    let part2 = do_the_thing(&maps, seeds.chunks(2).map(|chunk| (chunk[0], chunk[1])).collect());
+    dbg!(part1, part2);
+
+    Ok(())
+}