1 files changed, 79 insertions, 0 deletions
diff --git a/2017/src/bin/day07.rs b/2017/src/bin/day07.rs
new file mode 100644
index 0000000..9d2d75a
--- /dev/null
+++ b/2017/src/bin/day07.rs
@@ -0,0 +1,79 @@
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::io::{self, Read};
+use std::rc::Rc;
+
+#[derive(Debug, Default, Clone)]
+struct Program {
+    weight: u32,
+    disc: Vec<Rc<RefCell<Program>>>,
+}
+
+fn solve1(input: &str) -> String {
+    let mut programs: HashMap<String, Rc<RefCell<Program>>> = HashMap::new();
+    for line in input.lines() {
+        let mut words = line.split_whitespace();
+
+        let name = words.next()
+            .unwrap()
+            .to_owned();
+        let weight = words.next()
+            .unwrap()
+            .trim_matches(&['(', ')'][..])
+            .parse()
+            .unwrap();
+
+        if words.next().is_none() {
+            programs.entry(name)
+                .or_insert_with(Default::default)
+                .borrow_mut()
+                .weight = weight;
+            continue;
+        }
+
+        let disc = words.map(|child| {
+            programs.entry(child.trim_right_matches(',').to_owned())
+                .or_insert_with(Default::default)
+                .clone()
+        }).collect();
+
+        let mut program = programs.entry(name)
+            .or_insert_with(Default::default)
+            .borrow_mut();
+        program.weight = weight;
+        program.disc = disc;
+    }
+
+    programs.into_iter()
+        .find(|&(_, ref p)| Rc::strong_count(p) == 1)
+        .unwrap()
+        .0
+}
+
+fn main() {
+    let mut input = String::new();
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    println!("Part 1: {}", solve1(&input));
+}
+
+#[test]
+fn part1() {
+    assert_eq!("tknk", solve1(
+"\
+pbga (66)
+xhth (57)
+ebii (61)
+havc (66)
+ktlj (57)
+fwft (72) -> ktlj, cntj, xhth
+qoyq (66)
+padx (45) -> pbga, havc, qoyq
+tknk (41) -> ugml, padx, fwft
+jptl (61)
+ugml (68) -> gyxo, ebii, jptl
+gyxo (61)
+cntj (57)
+"
+    ));
+}