Part 2

2023/rust/src/day2.rs

@@ -1,3 +1,5 @@
+use std::cmp::{max, min};
+
 use crate::prelude::*;
 
 extern crate nom;
@@ -32,6 +34,13 @@ struct RevealGroup {
     blue: Option<usize>,
 }
 
+impl RevealGroup {
+    fn power(&self) -> usize {
+        println!("reveal group power for {:?}", self);
+        self.red.unwrap_or(0) * self.green.unwrap_or(0) * self.blue.unwrap_or(0)
+    }
+}
+
 impl From<Vec<Reveal>> for RevealGroup {
     fn from(value: Vec<Reveal>) -> Self {
         // TODO: this obviously won't work if the vector contains multiple reveals of the same kind
@@ -58,6 +67,24 @@ struct Game {
     reveal_groups: Vec<RevealGroup>,
 }
 
+impl Game {
+    fn made_possible(&self) -> RevealGroup {
+        let mut red = 0;
+        let mut green = 0;
+        let mut blue = 0;
+        for rg in &self.reveal_groups {
+            red = max(rg.red.unwrap_or(0), red);
+            green = max(rg.green.unwrap_or(0), green);
+            blue = max(rg.blue.unwrap_or(0), blue);
+        }
+        RevealGroup {
+            red: Some(red),
+            green: Some(green),
+            blue: Some(blue),
+        }
+    }
+}
+
 fn int(input: &str) -> IResult<&str, usize> {
     map_res(take_while_m_n(1, 16, |c: char| c.is_numeric()), |s| {
         usize::from_str_radix(s, 10)
@@ -79,11 +106,9 @@ fn reveal_group(input: &str) -> IResult<&str, RevealGroup> {
 }
 
 fn game(input: &str) -> IResult<&str, Game> {
-    println!("that belle");
     let (input, id) = int(tag("Game ")(input)?.0)?;
     let (input, reveal_groups) = separated_list0(tag("; "), reveal_group)(tag(": ")(input)?.0)?;
 
-    println!("{id} {:?}", reveal_groups);
     Ok((input, Game { id, reveal_groups }))
 }
 
@@ -114,7 +139,10 @@ impl AoCSolution for Day2 {
     }
 
     fn part2(input: Self::Input) -> Self::Solution {
-        return 0;
+        input
+            .lines()
+            .map(|s| game(s).unwrap().1.made_possible().power())
+            .sum()
     }
 }
 
@@ -135,6 +163,16 @@ Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green"#
             ),
             8
         );
-        assert_eq!(Day2::part2(r#""#.into()), 0);
+        assert_eq!(
+            Day2::part2(
+                r#"Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green"#
+                    .into()
+            ),
+            2286
+        );
     }
 }