Fix Games methods to not take ownership of self

day2/src/part1.rs

@@ -23,14 +23,14 @@ impl Games {
                 .collect(),
         }
     }
-    fn valid_games(self) -> Vec<i32> {
+    fn valid_games(&self) -> Vec<i32> {
         self.games
             .iter()
             .filter(|m| m.valid())
             .map(|m| m.id)
             .collect()
     }
-    fn valid_sum(self) -> i32 {
+    fn valid_sum(&self) -> i32 {
         self.valid_games().iter().sum()
     }
 }