Part 1 Day 19

BLOG.md

@@ -1,5 +1,49 @@
 # What Am I Learning Each Day?
 
+### Day 19
+
+**Difficulty: 5/10 ★★★☆☆☆☆☆☆☆**
+
+**Time: ~2 hrs**
+
+**Run Time: ~-**
+
+I hate parsing these things.
+
+This was the biggest data structure I've done so far.  I'm reasonably happy with being able to use `Ordering` enum for the rule comparisons:
+
+```rust
+struct Compare<'a> {
+    // not sure how I could make this a key of a struct
+    key: &'a str,
+    cmp: Ordering,
+    num: usize,
+}
+// later...
+if let Some(test) = &rule.test {
+    let val = part.get(test.key).expect("thought we had this key");
+
+    if val.cmp(&test.num) == test.cmp {
+        cur = rule.goto;
+        break;
+    }
+}
+```
+
+I still don't understand what `reduce` is, so I keep using `fold` which has a similar API to JavaScript.
+
+I got `trim_matches` and `split` working with multiple values:
+
+```rust
+let trim: &[_] = &['{', '}'];
+let rule_symbols: &[_] = &['<', '>', ':'];
+
+for workflow in workflow_str.lines() {
+    let mut details = workflow.split(trim).tak
+```
+
+Though I still don't get what that `&[_]` type is, and why it can't be inferred.
+
 ### Day 18
 
 **Difficulty: 3/10 ★★★☆☆☆☆☆☆☆**

day-19/src/main.rs

@@ -98,10 +98,43 @@ impl<'a> System<'a> {
 
         Self { workflows, parts }
     }
+
+    fn get_ratings(&self) -> usize {
+        let mut approved: Vec<&HashMap<&str, usize>> = vec![];
+
+        for part in self.parts.iter() {
+            // start at 'in'
+            let mut cur = "in";
+
+            while cur != "A" && cur != "R" {
+                for rule in self.workflows.get(cur).expect("don't have cur").rules.iter() {
+                    if let Some(test) = &rule.test {
+                        let val = part.get(test.key).expect("thought we had this key");
+
+                        if val.cmp(&test.num) == test.cmp {
+                            cur = rule.goto;
+                            break;
+                        }
+                    } else {
+                        // just goto
+                        cur = rule.goto;
+                        break;
+                    }
+                }
+            }
+            if cur == "A" {
+                approved.push(part);
+            }
+        }
+
+        approved.iter().fold(0, |acc, e| {
+            acc + e["x"] + e["m"] + e["a"] + e["s"]
+        })
+    }
 }
 
-fn part_one() -> usize {
-    0
+fn part_one(system: &System) -> usize {
+    system.get_ratings()
 }
 
 fn part_two() -> usize {
@@ -113,9 +146,11 @@ fn main() {
     let start = Instant::now();
     let contents = fs::read_to_string("./src/input.txt").unwrap();
 
+    let system = System::new(&contents);
+
     if one {
         let now = Instant::now();
-        let ans = part_one();
+        let ans = part_one(&system);
         println!("Part one: {:?} {:?}", ans, now.elapsed());
     }
 
@@ -136,9 +171,10 @@ mod tests {
 
     #[test]
     fn test_part_one() {
-        let ans = part_one();
+        let system = System::new(EXAMPLE);
+        let ans = part_one(&system);
 
-        assert_eq!(ans, 0);
+        assert_eq!(ans, 19114);
     }
 
     #[test]