add day11

Author: mirsella

2024/day11/.gitignore

@@ -0,0 +1,19 @@
+input.txt
+flamegraph.svg
+perf.data*
+### Rust
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+

2024/day11/Cargo.toml

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+[package]
+name = "day11"
+authors = ["mirsella <[email protected]>"]
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = { workspace = true }
+itertools = { workspace = true }
+pathfinding = { workspace = true }
+rayon = { workspace = true }
+indexmap = { workspace = true }

2024/day11/src/main.rs

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+use std::collections::HashMap;
+
+fn part(input: &str, count: u64) -> u64 {
+    let mut stones = input
+        .split_whitespace()
+        .map(|s| (s.parse::<u64>().unwrap(), 1))
+        .collect::<HashMap<_, _>>();
+    for _ in 0..count {
+        let mut new = HashMap::with_capacity(stones.len());
+        for (k, v) in stones {
+            let kstr = k.to_string();
+            if k == 0 {
+                *new.entry(1).or_default() += v;
+            } else if kstr.len() % 2 == 0 {
+                let (a, b) = kstr.split_at(kstr.len() / 2);
+                *new.entry(a.parse().unwrap()).or_default() += v;
+                *new.entry(b.parse().unwrap()).or_default() += v;
+            } else {
+                *new.entry(k * 2024).or_default() += v;
+            }
+        }
+        stones = new;
+    }
+    stones.values().sum()
+}
+
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("Part 1: {}", part(input, 25));
+    println!("Part 2: {}", part(input, 75));
+}
+
+#[cfg(test)]
+mod tests {
+    const INPUT: &str = "125 17";
+    #[test]
+    fn part1() {
+        assert_eq!(super::part(INPUT, 25), 55312);
+    }
+}