Advent of Code solutions
Day 9
+149
-7
+143
-7
years/2024/src/day_9.rs
+143
-7
years/2024/src/day_9.rs
···
1
+
use advent_core::{day_stuff, ex_for_day, Day};
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2
2
-
use advent_core::{Day, day_stuff, ex_for_day};
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pub struct Day9;
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+
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#[derive(Clone, Debug)]
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pub enum Block {
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File(usize),
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Blank,
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}
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#[derive(Debug, Clone)]
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pub struct Disk {
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data: Vec<(Block, usize)>,
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}
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impl Disk {
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pub fn parse(input: &str) -> Self {
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let data = input
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.chars()
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.enumerate()
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.map(|(i, c)| {
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let size = c.to_string().parse::<usize>().unwrap();
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if i % 2 == 0 {
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(Block::File(i / 2), size)
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} else {
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(Block::Blank, size)
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}
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})
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.collect::<Vec<_>>();
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Self { data }
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}
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+
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pub fn checksum(&self) -> usize {
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self.data
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.iter()
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.enumerate()
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.fold(
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(0, 0_usize),
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|(current_index, total), (_, (block, size))| match block {
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Block::Blank => (current_index + size, total),
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Block::File(id) => (
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current_index + size,
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total
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+ (current_index..current_index + size)
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.map(|i| *id * i)
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.sum::<usize>(),
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),
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},
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)
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.1
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}
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+
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#[allow(unused)]
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pub fn display(&self) -> String {
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self.data
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.iter()
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.map(|(b, s)| match b {
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Block::Blank => ".".repeat(*s),
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Block::File(id) => id.to_string().repeat(*s),
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})
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.collect::<String>()
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}
3
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4
-
pub struct Day9;
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/// (position, size)
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pub fn iter_blanks_before(&self, i: usize) -> impl Iterator<Item = (usize, usize)> + use<'_> {
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self.data.iter().enumerate().filter_map(move |(j, b)| {
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if let (Block::Blank, b_amnt) = b
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&& j < i
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{
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Some((j, *b_amnt))
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} else {
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None
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}
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})
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}
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+
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/// If we inserted once
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/// Assumes i > j, j describes [Block::Blank], i describes [Block::File].
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pub fn swap_blocks(&mut self, i: usize, j: usize) -> bool {
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let a = self.data[i].clone();
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let b = self.data[j].clone();
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+
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if a.1 == b.1 {
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self.data.swap(i, j);
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false
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} else {
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if a.1 > b.1 {
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self.data[i].1 -= b.1;
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self.data[j].0 = a.0.clone();
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self.data.insert(i + 1, (b.0.clone(), a.1 - b.1));
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} else {
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self.data[j] = a.clone();
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self.data[i].0 = b.0.clone();
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self.data.insert(j + 1, (b.0.clone(), b.1 - a.1));
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}
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+
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true
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}
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}
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}
5
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6
102
impl Day for Day9 {
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day_stuff!(9, "1928", "2858", Disk);
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104
8
-
day_stuff!(9, "", "");
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fn part_1(mut input: Self::Input) -> Option<String> {
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let mut i = input.data.len() - 1;
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loop {
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if let (Block::File(_), _) = input.data[i] {
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let next_blank = input.iter_blanks_before(i).next();
110
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if let Some((j, _)) = next_blank {
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if input.swap_blocks(i, j) {
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i += 1;
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}
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}
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}
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if i == 0 {
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break;
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} else {
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i -= 1;
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}
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}
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+
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Some(input.checksum().to_string())
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}
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+
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fn part_2(mut input: Self::Input) -> Option<String> {
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let mut i = input.data.len() - 1;
128
+
129
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loop {
130
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if let (Block::File(_), size) = input.data[i] {
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let next_blank = input
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.iter_blanks_before(i)
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.find(|(_, b_amnt)| *b_amnt >= size);
134
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if let Some((j, _)) = next_blank {
135
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if input.swap_blocks(i, j) {
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i += 1;
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}
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}
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}
140
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if i == 0 {
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break;
142
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} else {
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i -= 1;
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+
}
145
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}
9
146
10
-
fn part_1(_input: Self::Input) -> Option<String> {
11
-
None
147
+
Some(input.checksum().to_string())
12
148
}
13
149
14
-
fn part_2(_input: Self::Input) -> Option<String> {
15
-
None
150
+
fn parse_input(input: &str) -> Self::Input {
151
+
Disk::parse(input.trim())
16
152
}
17
153
}
+1
years/2024/src/examples/day_9/1.txt
+1
years/2024/src/examples/day_9/1.txt
···
1
+
2333133121414131402
+1
years/2024/src/examples/day_9/2.txt
+1
years/2024/src/examples/day_9/2.txt
···
1
+
2333133121414131402
+2
years/2024/src/lib.rs
+2
years/2024/src/lib.rs