Well, I guess I've decided to do AoC this year. Trivial problem, though I shamelessly stole some range-merging code from AoC 2022 (it was when I was still well in the learning phase of Rust). If you can't look at old code and wonder WTF you were thinking, have you really gotten any better?
Solution (mostly uninteresting)
pub fn day05(input: &str) -> (u64, u64) {
let mut part1 = 0;
let mut part2 = 0;
let mut ranges = Vec::new();
let mut lines = input.trim().lines();
for line in lines.by_ref() {
if line.is_empty() {
break;
}
let range = line
.split_once('-')
.map(|(l, h)| [l.parse::<u64>().unwrap(), h.parse::<u64>().unwrap()])
.unwrap();
ranges.push(range);
}
let ranges = combine_ranges(ranges);
for idx in lines {
for r in ranges.iter() {
if (r[0]..=r[1]).contains(&idx.parse::<u64>().unwrap()) {
part1 += 1;
break;
}
}
}
for r in ranges {
part2 += r[1] - r[0] + 1;
}
(part1, part2)
}
combine_ranges WARNING : Hideous, triggers Clippy, not blazingly fast
fn combine_ranges(ranges: Vec<[u64; 2]>) -> Vec<[u64; 2]> {
let mut temp_ranges = ranges;
let mut comp_ranges: Vec<[u64; 2]> = Vec::new();
let mut run_again: bool = true;
while run_again {
run_again = false;
comp_ranges = Vec::new();
'outer: for i in 0..temp_ranges.len() {
for j in 0..comp_ranges.len() {
if temp_ranges[i][0] <= comp_ranges[j][0] && comp_ranges[j][1] <= temp_ranges[i][1]
{
//temp covers all of comp
comp_ranges[j][0] = temp_ranges[i][0];
comp_ranges[j][1] = temp_ranges[i][1];
run_again = true;
continue 'outer;
} else if comp_ranges[j][0] <= temp_ranges[i][0]
&& temp_ranges[i][1] <= comp_ranges[j][1]
{
//comp covers all of temp
run_again = true;
continue 'outer;
} else if temp_ranges[i][0] <= comp_ranges[j][0]
&& comp_ranges[j][0] <= temp_ranges[i][1]
&& temp_ranges[i][1] <= comp_ranges[j][1]
{
//grow left
comp_ranges[j][0] = temp_ranges[i][0];
run_again = true;
continue 'outer;
} else if comp_ranges[j][0] <= temp_ranges[i][0]
&& temp_ranges[i][0] <= comp_ranges[j][1]
&& comp_ranges[j][1] <= temp_ranges[i][1]
{
//grow right
comp_ranges[j][1] = temp_ranges[i][1];
run_again = true;
continue 'outer;
}
}
comp_ranges.push(temp_ranges[i]);
}
temp_ranges = comp_ranges.clone();
}
comp_ranges
}