puzzles/day_7: Implement part 2

Signed-off-by: Jim Gerth <[email protected]>

src/puzzles/day_7.rs

@@ -1,5 +1,4 @@
 use std::collections::{HashMap, HashSet};
-use std::iter::FromIterator;
 
 use regex::Regex;
 
@@ -49,7 +48,7 @@ pub fn part_1() -> i32 {
         contained_in_rules.insert(bag_color, HashSet::new());
     }
 
-    println!("{:#?}", can_contain_rules);
+    // println!("{:#?}", can_contain_rules);
 
     // Invert rules.
     for (color, contained_colors) in can_contain_rules.iter() {
@@ -61,11 +60,11 @@ pub fn part_1() -> i32 {
         }
     }
 
-    println!("{:#?}", contained_in_rules);
+    // println!("{:#?}", contained_in_rules);
 
     let containers = get_containers("shiny gold", &contained_in_rules);
 
-    println!("{:#?}", containers);
+    // println!("{:#?}", containers);
 
     containers.len() as i32
 }
@@ -88,5 +87,67 @@ fn get_containers<'a>(
 }
 
 pub fn part_2() -> i32 {
-    5
+    let input = input::read_lines(7);
+    let mut rules: HashMap<&str, HashMap<&str, i32>> = HashMap::new();
+
+    let bag_color_regex = Regex::new(r"^\w* \w*").unwrap();
+    let bag_rules_regex = Regex::new(r"bags contain (.*).").unwrap();
+    let bag_rule_regex = Regex::new(r"(\d+) (\w+ \w+) \w+").unwrap();
+
+    // Parse rules.
+    for line in &input {
+        let bag_color = bag_color_regex
+            .captures(line)
+            .unwrap()
+            .get(0)
+            .unwrap()
+            .as_str();
+        let bag_rules = bag_rules_regex
+            .captures(line)
+            .unwrap()
+            .get(1)
+            .unwrap()
+            .as_str();
+
+        let bag_rules: HashMap<&str, i32> = if bag_rules != "no other bags" {
+            bag_rules
+                .split(", ")
+                .map(|rule| {
+                    (
+                        bag_rule_regex
+                            .captures(rule)
+                            .unwrap()
+                            .get(2)
+                            .unwrap()
+                            .as_str(),
+                        bag_rule_regex
+                            .captures(rule)
+                            .unwrap()
+                            .get(1)
+                            .unwrap()
+                            .as_str()
+                            .parse()
+                            .unwrap(),
+                    )
+                })
+                .collect()
+        } else {
+            HashMap::new()
+        };
+
+        rules.insert(bag_color, bag_rules);
+    }
+
+    // println!("{:#?}", rules);
+
+    get_content_count("shiny gold", &rules)
+}
+
+fn get_content_count(color: &str, rules: &HashMap<&str, HashMap<&str, i32>>) -> i32 {
+    let rule = rules.get(color).expect("Color not listed in rules.");
+    let mut total = 0;
+    for (color, count) in rule {
+        total += count + count * get_content_count(color, &rules);
+    }
+    total
 }