Day2

day2/rust/Cargo.lock

@@ -0,0 +1,25 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "rust"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]

day2/rust/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+itertools = "0.13.0"

day2/rust/src/main.rs

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+use itertools::Itertools;
+
+fn main() {
+    let stdin = std::io::stdin();
+    let mut input = Vec::new();
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let levels: Vec<_> = line
+            .split_whitespace()
+            .map(|e| e.parse::<isize>().unwrap())
+            .collect();
+
+        input.push(levels);
+    }
+
+    println!("{}", input.iter().filter(|e| is_safe(e)).count());
+
+    println!(
+        "{}",
+        input
+            .iter()
+            .map(|levels| {
+                levels.iter().combinations(levels.len() - 1).any(|e| {
+                    let combination: Vec<_> = e.into_iter().copied().collect();
+                    is_safe(&combination)
+                })
+            })
+            .filter(|&e| e)
+            .count()
+    );
+}
+
+fn is_safe(levels: &Vec<isize>) -> bool {
+    if levels.len() < 2 {
+        return true;
+    }
+
+    let direction = levels[1] - levels[0];
+
+    return levels
+        .iter()
+        .tuple_windows()
+        .filter(|&(a, b)| (b - a).abs() < 1 || (b - a).abs() > 3 || (b - a) * direction < 0)
+        .count()
+        == 0;
+}