Prepare day 4

2020/src/day04.rs

@@ -0,0 +1,12 @@
+use std::io::Read;
+
+use crate::Solution;
+
+#[derive(Default)]
+pub struct Day04;
+
+impl Solution for Day04 {
+    fn part1(&mut self, input: &mut dyn Read) -> String {
+        todo!()
+    }
+}

2020/src/lib.rs

@@ -4,6 +4,7 @@ mod common;
 mod day01;
 mod day02;
 mod day03;
+mod day04;
 
 pub trait Solution {
     fn part1(&mut self, input: &mut dyn Read) -> String;