haselkern/aoc2024
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Solve 09

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This commit is contained in:
Lars Martens 2024-12-09 23:08:30 +01:00
parent b48d010302
commit 452c9d350d
Signed by: haselkern
GPG key ID: B5CF1F363C179AD4
1 changed files with 71 additions and 13 deletions
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84
src/bin/09.rs
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@ -1,3 +1,4 @@
use std::cmp::Ordering;
use std::collections::VecDeque;
use aoc::*;
@ -5,14 +6,69 @@ use aoc::*;
const INPUT: &str = include_str!("../../input/09");
fn main() {
assert_example!(part1, "09-test", 0);
assert_example!(part1, "09-test", 1928);
println!("Part 1: {}", part1(INPUT));
assert_example!(part2, "09-test", 2858);
println!("Part 2: {}", part2(INPUT));
}
fn part1(_input: &str) -> usize {
0 // TODO Paste solution from other machine…
fn part1(input: &str) -> usize {
let mut disk_map = parse(input);
let mut map_index = 0;
let mut checksum = 0;
'checksum: while let Some(block) = disk_map.pop_front() {
match block {
Block::Free {
length: mut free_space,
..
} => {
// Fill free space
let mut fill = Vec::new();
while free_space > 0 {
let Some(tail) = disk_map.pop_back() else {
break 'checksum;
};
match tail {
Block::Free { .. } => (), // Remove free space from the end
Block::File(File {
id,
length,
position,
}) => {
let insert_length = free_space.min(length);
free_space -= insert_length;
let remaining_length = length - insert_length;
fill.push(Block::File(File {
position,
id,
length: insert_length,
}));
if remaining_length > 0 {
disk_map.push_back(Block::File(File {
position,
id,
length: remaining_length,
}));
}
}
}
}
for block in fill.into_iter().rev() {
disk_map.push_front(block);
}
}
Block::File(File { id, length, .. }) => {
for _ in 0..length {
checksum += id * map_index;
map_index += 1;
}
}
}
}
checksum
}
fn part2(input: &str) -> usize {
@ -29,8 +85,8 @@ fn part2(input: &str) -> usize {
}) => {
// Find free space to put file
let mut space = None;
for i in 0..disk.len() {
if let Block::Free { position, length } = disk[i] {
for (i, &block) in disk.iter().enumerate() {
if let Block::Free { position, length } = block {
if length >= file_length {
space = Some((i, position, length));
break;
@ -56,15 +112,17 @@ fn part2(input: &str) -> usize {
});
// Adjust remaining space
if space_length == file_length {
disk.remove(space_index);
} else if space_length > file_length {
disk[space_index] = Block::Free {
position: space_position + file_length,
length: space_length - file_length,
match space_length.cmp(&file_length) {
Ordering::Equal => {
disk.remove(space_index);
}
} else {
panic!("this should not be possible");
Ordering::Greater => {
disk[space_index] = Block::Free {
position: space_position + file_length,
length: space_length - file_length,
};
}
Ordering::Less => panic!("this should not be possible"),
}
}
}