day 19 b

src/day19.rs

@@ -1,4 +1,4 @@
-use std::collections::{HashSet, VecDeque};
+use std::collections::HashSet;
 
 use aoc_runner_derive::{aoc, aoc_generator};
 
@@ -49,26 +49,12 @@ fn starts(a: &str, pattern: &str) -> Vec<usize> {
 }
 
 #[aoc(day19, part2)]
-fn part2((transformations, target): &(Vec<Transformation>, String)) -> usize {
-    search("e", transformations, target)
-}
-
-fn search(base: &str, transformations: &[Transformation], target: &str) -> usize {
-    let mut seen = HashSet::new();
-    seen.insert(base.to_string());
-    let mut queue = VecDeque::new();
-    queue.push_back((base.to_string(), 0));
-    while let Some((from, depth)) = queue.pop_front() {
-        for possibility in possibilities(transformations, &from) {
-            if possibility == target {
-                return depth + 1;
-            }
-            if seen.insert(possibility.clone()) {
-                queue.push_back((possibility, depth + 1));
-            }
-        }
-    }
-    unreachable!("No solution was found");
+fn part2((_transformations, target): &(Vec<Transformation>, String)) -> usize {
+    let l = target.chars().filter(|c| c.is_uppercase()).count();
+    let cy = target.chars().filter(|c| *c == 'Y').count();
+    let crn = target.split("Rn").count() - 1;
+    let car = target.split("Ar").count() - 1;
+    l - crn - car - 2 * cy - 1
 }
 
 #[cfg(test)]