feat(04/2015): solve second part

Author: manhunto

readme.md

@@ -90,7 +90,7 @@
 | [Day 1: Not Quite Lisp](src/solutions/year2015/day01.rs)                         |   ⭐⭐   |            0.013 |            0.001 |
 | [Day 2: I Was Told There Would Be No Math](src/solutions/year2015/day02.rs)      |   ⭐⭐   |            0.074 |            0.105 |
 | [Day 3: Perfectly Spherical Houses in a Vacuum](src/solutions/year2015/day03.rs) |   ⭐⭐   |            0.358 |            0.373 |
-| [Day 4: The Ideal Stocking Stuffer](src/solutions/year2015/day04.rs)             |   ⭐    |           66.769 |                - |
+| [Day 4: The Ideal Stocking Stuffer](src/solutions/year2015/day04.rs)             |   ⭐⭐   |           66.769 |         1931.428 |
 
 # TODO
 

src/solutions/year2015/day04.rs

@@ -5,22 +5,28 @@ pub struct Day04;
 
 impl Solution for Day04 {
     fn part_one(&self, input: &str) -> String {
+        self.answer(input, "00000")
+    }
+
+    fn part_two(&self, input: &str) -> String {
+        self.answer(input, "000000")
+    }
+}
+
+impl Day04 {
+    fn answer(&self, input: &str, starts_with: &str) -> String {
         (0u64..)
             .find(|answer| {
                 let hash = format!("{}{}", input, answer);
                 let digest = compute(hash);
 
                 let x = format!("{:x}", digest);
 
-                x.starts_with("00000")
+                x.starts_with(starts_with)
             })
             .unwrap()
             .to_string()
     }
-
-    fn part_two(&self, _input: &str) -> String {
-        String::from("0")
-    }
 }
 
 #[cfg(test)]