2024: Day 25

michel-kraemer · michel-kraemer · commit 7ca37847c63e · 2024-12-25T06:45:34.000+01:00
Part 1: 00:12:42 / Rank 1150
Part 2: 00:12:49 / Rank 959
diff --git a/2024/day25/.vscode/settings.json b/2024/day25/.vscode/settings.json
@@ -0,0 +1,7 @@
+{
+  "[rust]": {
+    "editor.defaultFormatter": "rust-lang.rust-analyzer",
+    "editor.formatOnSave": true
+  },
+  "rust-analyzer.check.command": "clippy"
+}
diff --git a/2024/day25/Cargo.lock b/2024/day25/Cargo.lock
diff --git a/2024/day25/Cargo.toml b/2024/day25/Cargo.toml
@@ -0,0 +1,4 @@
+[package]
+name = "day25"
+version = "0.1.0"
+edition = "2021"
diff --git a/2024/day25/src/main.rs b/2024/day25/src/main.rs
@@ -0,0 +1,48 @@
+use std::fs;
+
+fn main() {
+    let input = fs::read_to_string("input.txt").expect("Could not read file");
+
+    let grids = input.split("\n\n").collect::<Vec<_>>();
+
+    let mut locks = Vec::new();
+    let mut keys = Vec::new();
+
+    // decide which grids are locks and which are keys and calculate pin heights
+    let mut total_height = 0;
+    for g in grids.iter() {
+        let g = g
+            .lines()
+            .map(|l| l.chars().collect::<Vec<_>>())
+            .collect::<Vec<_>>();
+        let is_key = g[0][0] != '#';
+        total_height = g.len();
+
+        let mut heights = vec![0usize; g[0].len()];
+        for row in g {
+            for (x, c) in row.iter().enumerate() {
+                if *c == '#' {
+                    heights[x] += 1;
+                }
+            }
+        }
+
+        if is_key {
+            keys.push(heights);
+        } else {
+            locks.push(heights);
+        }
+    }
+
+    // check which key fits into which lock
+    let mut total = 0;
+    for k in &keys {
+        for l in &locks {
+            if k.iter().zip(l).all(|(a, b)| a + b <= total_height) {
+                total += 1;
+            }
+        }
+    }
+
+    println!("{}", total);
+}
