Implement 2025 - Day 11 - Part 1

2025/11.rs

@@ -0,0 +1,57 @@
+---cargo
+[profile.dev]
+opt-level = 3
+
+[dependencies]
+nalgebra = "0.34"
+---
+
+use nalgebra::DMatrix;
+use std::collections::HashMap;
+
+static CONTENT: &'static str = include_str!("./inputs/11_1.txt");
+
+fn main() {
+    let parts: HashMap<[char; 3], (usize, Vec<[char; 3]>)> = CONTENT.lines().map(|l| l.trim()).map(|p| {
+        let (key, rest) = p.split_once(':').unwrap();
+        let key = key.trim();
+        let rest = rest.trim();
+
+        let key: [char; 3] = core::array::from_fn(|idx| key.chars().nth(idx).unwrap());
+        let rest: Vec<[char; 3]> = rest.split(' ').map(|p| {
+            core::array::from_fn(|idx| p.chars().nth(idx).unwrap())
+        }).collect();
+
+        (key, rest)
+    }).chain([(['o', 'u', 't'], Vec::new())]).enumerate().map(|(idx, (key, v))| (key, (idx, v))).collect();
+
+    println!("{:?}", parts);
+
+    let mut adj_matrix = DMatrix::from_element(parts.len(), parts.len(), 0u64);
+
+    for (src, (src_idx, targets)) in parts.iter() {
+        for dest_idx in targets.iter().map(|t| parts.get(t).map(|(i, _)| i).unwrap()) {
+            adj_matrix[(*src_idx, *dest_idx)] = 1;
+        }
+    }
+
+    println!("{}", adj_matrix);
+
+    let you_idx: usize = parts.get(&['y', 'o', 'u']).map(|(idx, _)| *idx).unwrap();
+    let out_idx: usize = parts.get(&['o', 'u', 't']).map(|(idx, _)| *idx).unwrap();
+
+    let mut total_routes = 0;
+
+    let mut connectivity_matrix = DMatrix::identity(parts.len(), parts.len());
+    for length in 1..=parts.len() {
+        println!("Length: {:?}", length);
+        connectivity_matrix *= &adj_matrix;
+
+        let routes: u64 = connectivity_matrix[(you_idx, out_idx)];
+        println!("Routes: {}", routes);
+
+        total_routes += routes;
+    }
+
+    println!("Total Routes: {}", total_routes);
+}