chore: y2024::day_09

Author: clechasseur

.run/run_aoc.run.xml

@@ -0,0 +1,20 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="run_aoc" type="CargoCommandRunConfiguration" factoryName="Cargo Command">
+    <option name="buildProfileId" value="dev" />
+    <option name="command" value="run --package aoclp_solutions --bin aoclp_solutions -- --year 2024 --day 9" />
+    <option name="workingDirectory" value="file://$PROJECT_DIR$" />
+    <envs />
+    <option name="emulateTerminal" value="true" />
+    <option name="channel" value="DEFAULT" />
+    <option name="requiredFeatures" value="true" />
+    <option name="allFeatures" value="true" />
+    <option name="withSudo" value="false" />
+    <option name="buildTarget" value="REMOTE" />
+    <option name="backtrace" value="SHORT" />
+    <option name="isRedirectInput" value="false" />
+    <option name="redirectInputPath" value="" />
+    <method v="2">
+      <option name="CARGO.BUILD_TASK_PROVIDER" enabled="true" />
+    </method>
+  </configuration>
+</component>

aoclp_solutions/src/lib.rs

@@ -10,6 +10,6 @@ pub mod y2025;
 
 build_solvers! {
     { 2017, [01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25] },
-    { 2024, [01, 02, 03, 04, 05, 06, 07, 08] },
+    { 2024, [01, 02, 03, 04, 05, 06, 07, 08, 09] },
     { 2025, [01, 02, 03, 04, 05, 06] }
 }

aoclp_solutions/src/y2024/day_09.rs

@@ -0,0 +1,113 @@
+use aoclp::solvers_impl::input::safe_get_input;
+use itertools::repeat_n;
+use strum::{EnumCount, EnumIs, FromRepr};
+
+pub fn part_1() -> usize {
+    let mut blocks = blocks();
+    defrag_blocks(&mut blocks);
+    checksum(blocks)
+}
+
+pub fn part_2() -> usize {
+    let mut blocks = blocks();
+    defrag_files(&mut blocks);
+    checksum(blocks)
+}
+
+type Block = Option<usize>;
+
+#[repr(usize)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, EnumIs, EnumCount, FromRepr)]
+enum BlockType {
+    EmptySpace,
+    File,
+}
+
+impl BlockType {
+    fn block(self, id: usize) -> Block {
+        self.is_file().then_some(id)
+    }
+
+    fn next_id(self, id: usize) -> usize {
+        id + self as usize
+    }
+
+    fn next_type(self) -> Self {
+        Self::from_repr((self as usize + 1) % Self::COUNT).unwrap()
+    }
+}
+
+fn blocks() -> Vec<Block> {
+    input()
+        .chars()
+        .fold((Vec::new(), 0, BlockType::File), |(mut acc, id, block_type), c| {
+            let len = c.to_digit(10).unwrap() as usize;
+            acc.extend(repeat_n(block_type.block(id), len));
+            (acc, block_type.next_id(id), block_type.next_type())
+        })
+        .0
+}
+
+fn defrag_blocks(blocks: &mut [Block]) {
+    let mut i = 0;
+    let mut last = blocks.len() - 1;
+    while i <= last {
+        if blocks[i].is_none() {
+            while blocks[last].is_none() {
+                last -= 1;
+            }
+            blocks[i] = blocks[last].take();
+            last -= 1;
+        }
+        i += 1;
+    }
+}
+
+fn defrag_files(blocks: &mut Vec<Block>) {
+    let mut i = blocks.len() - 1;
+    while i > 0 {
+        if let Some(id) = blocks[i] {
+            let mut start = i;
+            while start > 0 && blocks[start - 1].is_some_and(|block| block == id) {
+                start -= 1;
+            }
+            if start == 0 {
+                break;
+            }
+            let block_len = i - start + 1;
+
+            let mut target = 0;
+            while target < start
+                && blocks[target..target + block_len]
+                    .iter()
+                    .any(Option::is_some)
+            {
+                target += 1;
+            }
+            if target < start {
+                blocks.splice(start..=i, repeat_n(None, block_len));
+                blocks.splice(target..target + block_len, repeat_n(Some(id), block_len));
+            }
+
+            i = start - 1;
+        } else {
+            i -= 1;
+        }
+    }
+}
+
+fn checksum<B>(blocks: B) -> usize
+where
+    B: IntoIterator<Item = Block>,
+{
+    blocks
+        .into_iter()
+        .enumerate()
+        .fold(0, |acc, (i, block)| acc + block.map_or(0, |id| id * i))
+}
+
+const EXAMPLE: &str = "2333133121414131402";
+
+fn input() -> String {
+    safe_get_input(2024, 9)
+}

aoclp_solutions/src/y2024/mod.rs

@@ -6,3 +6,4 @@ pub mod day_05;
 pub mod day_06;
 pub mod day_07;
 pub mod day_08;
+pub mod day_09;