Add solver constants

src/solvers/playground.rs

@@ -8,6 +8,7 @@ pub struct Playground {
 }
 
 impl Playground {
+    const POINT_SPLIT_CHAR: char = ',';
     const CIRCUITS_TAKE: usize = 3;
 
     pub fn new(connections: Option<usize>) -> Playground {
@@ -20,7 +21,7 @@ impl Playground {
     fn junction_boxes<R: BufRead>(reader: R) -> Vec<Point3> {
         let mut junction_boxes = Vec::new();
         for line in reader.lines().map_while(Result::ok) {
-            let j: Vec<u64> = line.split(',').map(|s| s.parse().unwrap()).collect();
+            let j: Vec<u64> = line.split(Self::POINT_SPLIT_CHAR).map(|s| s.parse().unwrap()).collect();
             junction_boxes.push(Point3(j[0], j[1], j[2]));
         }
         junction_boxes