nove.dev
retroactive, to derust my rust
day9 part2
+88
-7
src/day9.rs
+88
-7
src/day9.rs
···
2
2
let diskmap = parse(input);
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3
let mut blocks = diskmap_to_blocks(&diskmap);
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compact(&mut blocks);
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-
let sum = blocks
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.into_iter()
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.flatten()
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.enumerate()
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.map(|(index, block)| index as u64 * block)
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.sum::<u64>();
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+
let sum = checksum(&blocks);
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sum.to_string()
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}
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8
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9
pub fn day9_part2(input: &str) -> String {
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-
todo!()
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+
let diskmap = parse(input);
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+
let compacted_diskmap = defrag_compact(&diskmap);
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let blocks = compacted_diskmap_to_blocks(&compacted_diskmap);
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let sum = checksum(&blocks);
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sum.to_string()
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}
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+
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#[derive(Copy, Clone, PartialEq, Eq, Debug)]
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struct File {
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id: u64,
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length: usize,
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free_space: usize,
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}
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+
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fn compacted_diskmap_to_blocks(compacted_diskmap: &[File]) -> Vec<Option<u64>> {
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compacted_diskmap
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.iter()
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.flat_map(|file| {
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[
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vec![Some(file.id); file.length],
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vec![None; file.free_space],
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]
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})
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.flatten()
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.collect()
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}
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+
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fn defrag_compact(diskmap: &[usize]) -> Vec<File> {
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let files = diskmap_to_files(diskmap);
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let mut compacted_files = files.clone();
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+
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for file in files.clone().into_iter().rev() {
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let Some(insertable_index) = compacted_files
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.iter()
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.enumerate()
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.find(|(_, insertable_file)| insertable_file.free_space >= file.length)
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.map(|(i, _)| i)
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else {
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continue;
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};
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+
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let prev_free_space = compacted_files[insertable_index].free_space;
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compacted_files[insertable_index].free_space = 0;
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compacted_files.insert(insertable_index + 1, file);
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compacted_files[insertable_index + 1].free_space = prev_free_space - file.length;
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+
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let nullable_index = compacted_files
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.iter()
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.enumerate()
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.rev()
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.find(|(_, nullable_file)| nullable_file.id == file.id)
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.map(|(i, _)| i)
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.unwrap();
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compacted_files[nullable_index - 1].free_space +=
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compacted_files[nullable_index].length + compacted_files[nullable_index].free_space;
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compacted_files.remove(nullable_index);
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}
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+
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compacted_files
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}
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+
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fn diskmap_to_files(diskmap: &[usize]) -> Vec<File> {
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let mut id = 0u64;
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let mut blocks = vec![];
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+
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for digit in diskmap {
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if id % 2 == 0 {
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blocks.push(File {
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id: id / 2,
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length: *digit,
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free_space: 0,
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});
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} else {
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blocks.last_mut().unwrap().free_space = *digit;
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}
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id += 1
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}
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+
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+
blocks
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+
}
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+
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fn checksum(blocks: &[Option<u64>]) -> u64 {
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blocks
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.iter()
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.enumerate()
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.map(|(index, block)| if let Some(block) = block {index as u64 * block} else {0})
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.sum::<u64>()
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97
}
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fn diskmap_to_blocks(diskmap: &[usize]) -> Vec<Option<u64>> {
+7
-7
src/lib.rs
+7
-7
src/lib.rs
···
357
357
let result = day9::day9_part1(include_str!("../input/day9.txt"));
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assert_eq!(result, "6448989155953");
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359
}
360
-
// #[test]
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// fn day9_part2_test() {
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// let test_result = day9::day9_part2(include_str!("../input/day9.test.txt"));
363
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// assert_eq!(test_result, "34");
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// // let result = day9::day9_part2(include_str!("../input/day9.txt"));
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// // assert_eq!(result, "1169");
366
-
// }
360
+
#[test]
361
+
fn day9_part2_test() {
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let test_result = day9::day9_part2(include_str!("../input/day9.test.txt"));
363
+
assert_eq!(test_result, "2858");
364
+
let result = day9::day9_part2(include_str!("../input/day9.txt"));
365
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assert_eq!(result, "6476642796832");
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+
}
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#[test]
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369
fn day8_part1_test() {