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static DAY: u8 = 5;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", lowest_location(&input));
println!("{DAY}b: {}", lowest_location2(&input));
}
#[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 read_range_map(input: &[String]) -> Vec<RangeCategory> {
let mut range_maps = Vec::new();
let mut current_category = Vec::new();
for line in input.iter() {
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() });
range_maps
}
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 range_maps = read_range_map(&input[2..]);
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()
}
fn lowest_location2(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 range_maps = read_range_map(&input[2..]);
let mut lowest_location = u64::max_value();
for (i, start) in seeds.iter().enumerate().step_by(2) {
let range = seeds[i+1];
for seed in *start..start+range {
let mut next_val = seed;
for category in &range_maps {
next_val = category.map(next_val);
}
lowest_location = std::cmp::min(next_val, lowest_location)
}
}
lowest_location
}
#[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);
assert_eq!(lowest_location2(&input), 46);
}
}
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