day08 part 1

src/tasks/day08.rs

@@ -0,0 +1,47 @@
+use crate::utils;
+
+pub fn task1() {
+    let input: Vec<usize> = utils::read_file("input/day08.txt")
+        .split(" ")
+        .map(|x| x.parse().unwrap())
+        .collect();
+
+    let (tree, rest) = Node::extract_from(&input);
+    println!("Metadata sum: {}", tree.metadata_sum());
+    println!("rest: {:?}", rest);
+}
+
+struct Node {
+    metadata: Vec<usize>,
+    children: Vec<Node>,
+}
+
+impl Node {
+    fn extract_from(input: &[usize]) -> (Self, &[usize]) {
+        let mut rest_input = &input[2..];
+        let mut num_children: usize = input[0];
+        let num_meta: usize = input[1];
+        let mut children = Vec::new();
+        while num_children > 0 {
+            let (node, rest) = Node::extract_from(&rest_input);
+            children.push(node);
+            rest_input = rest;
+            num_children -= 1;
+        }
+
+        let metadata = rest_input[..num_meta].iter().map(|x| *x).collect();
+        (Node { metadata, children }, &rest_input[num_meta..])
+    }
+
+    fn metadata_sum(&self) -> usize {
+        self.metadata.iter().sum::<usize>()
+            + self
+                .children
+                .iter()
+                .map(|child| {
+                    let s: usize = child.metadata_sum().clone();
+                    s
+                })
+                .sum::<usize>()
+    }
+}