Implement day 05.

This was a nice exercise in not allocating memory. Or at least it was,
for part 1.

2018/src/main.rs

@@ -11,6 +11,7 @@ pub mod day01;
 pub mod day02;
 pub mod day03;
 pub mod day04;
+pub mod day05;
 
 fn get_impl(day: &str) -> Box<common::Solution> {
     match day.parse() {
@@ -18,6 +19,7 @@ fn get_impl(day: &str) -> Box<common::Solution> {
         Ok(2) => Box::new(day02::Day02::new()),
         Ok(3) => Box::new(day03::Day03::new()),
         Ok(4) => Box::new(day04::Day04::new()),
+        Ok(5) => Box::new(day05::Day05::new()),
         Ok(val) => panic!("Unimplemented day {}", val),
         _ => panic!("Invalid number"),
     }
@@ -63,7 +65,7 @@ mod tests {
     #[test]
     fn test_get_impl() {
         // Verify that we can load all days
-        let last_implemented = 4;
+        let last_implemented = 5;
         for d in 1..=last_implemented {
             get_impl(&format!("{}", d));
         }