Now that it's DFS, no point in preallocating much room for the stack

README.md

@@ -53,9 +53,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 16](./src/bin/16.rs) | `58.3µs` | `1.7ms` |
 | [Day 17](./src/bin/17.rs) | `1.6ms` | `3.7ms` |
 | [Day 18](./src/bin/18.rs) | `2.4µs` | `2.5µs` |
-| [Day 19](./src/bin/19.rs) | `167.4µs` | `159.5µs` |
+| [Day 19](./src/bin/19.rs) | `167.6µs` | `156.8µs` |
 
-**Total: 14.41ms**
+**Total: 14.40ms**
 <!--- benchmarking table --->
 
 ---

src/bin/19.rs

@@ -37,7 +37,7 @@ pub fn part_two(input: &str) -> Option<u64> {
 
     // DFS until we find accept nodes. Each path to an accept node results
     // in a volume of possible ratings. The union of those volumes is our answer.
-    let mut stack = Vec::with_capacity(1000);
+    let mut stack = Vec::new();
     stack.push(("in", PartFilter::new(1, 4000)));
     let mut volume = 0;
     while let Some((cur, filter)) = stack.pop() {