day 7 part 2 solution

Signed-off-by: Stephen Waits <swaits@amazon.com>

data/output-07.txt

@@ -1,2 +1,2 @@
 229
-0
+6683

src/day07.rs

@@ -2,10 +2,7 @@
 
 use crate::utils;
 use anyhow::Result;
-use std::{
-    collections::{HashMap, HashSet},
-    iter::{self, FromIterator},
-};
+use std::collections::HashMap;
 
 // light red bags contain 1 bright white bag, 2 muted yellow bags.
 // dark orange bags contain 3 bright white bags, 4 muted yellow bags.
@@ -17,27 +14,28 @@ use std::{
 // faded blue bags contain no other bags.
 // dotted black bags contain no other bags.
 
+struct PurseQuantity<'a>(usize, &'a str);
+
 // parse data into a HashMap<&str, Vec<&str>>
 //
 // for example: "light red bags contain 1 bright white bag, 2 muted yellow bags."
 // becomes: { "light red": ["bright white", "muted yellow", "muted yellow"]}
 //
-fn parse(s: &str) -> HashMap<&str, Vec<&str>> {
+fn parse(s: &str) -> HashMap<&str, Vec<PurseQuantity>> {
     s.lines()
         .map(|l| {
             let parsed: Vec<&str> = l.splitn(2, " bags contain ").collect();
             let container = parsed[0];
-            let contents: Vec<&str> = match parsed[1].trim() {
+            let contents: Vec<PurseQuantity> = match parsed[1].trim() {
                 "no other bags." => Vec::new(),
                 _ => parsed[1]
                     .trim_end_matches('.')
                     .split(',')
-                    .flat_map(|c| {
+                    .map(|c| {
                         let trimmed = c.trim_end_matches("bags").trim_end_matches("bag").trim();
                         let count: usize = trimmed[0..1].parse().unwrap();
                         let purse = &trimmed[2..];
-                        let seq: Vec<&str> = iter::repeat(purse).take(count).collect();
-                        seq
+                        PurseQuantity(count, purse)
                     })
                     .collect(),
             };
@@ -46,15 +44,22 @@ fn parse(s: &str) -> HashMap<&str, Vec<&str>> {
         .collect()
 }
 
-fn has_contents(data: &HashMap<&str, Vec<&str>>, container: &str, contents: &str) -> bool {
-    let these_contents: HashSet<&str> =
-        HashSet::from_iter(data.get(&container).unwrap().iter().cloned());
+fn has_contents(data: &HashMap<&str, Vec<PurseQuantity>>, container: &str, contents: &str) -> bool {
+    let these_contents: &Vec<&str> = &data.get(&container).unwrap().iter().map(|c| c.1).collect();
     these_contents.contains(&contents)
         || these_contents
             .iter()
             .any(|m| has_contents(data, m, contents))
 }
 
+fn count_contents(data: &HashMap<&str, Vec<PurseQuantity>>, container: &str) -> usize {
+    let these_contents: &Vec<PurseQuantity> = &data.get(&container).unwrap();
+    these_contents
+        .iter()
+        .map(|c| c.0 + c.0 * count_contents(data, c.1))
+        .sum()
+}
+
 pub fn run() -> Result<(usize, usize)> {
     let data = utils::read_file("data/input-07.txt")?;
     let answers = utils::read_i64s("data/output-07.txt")?;
@@ -66,6 +71,9 @@ pub fn run() -> Result<(usize, usize)> {
         .filter(|k| has_contents(&parsed, k, "shiny gold"))
         .count();
 
+    let p2 = count_contents(&parsed, "shiny gold");
+
     assert_eq!(p1, answers[0] as usize);
-    Ok((p1, 0))
+    assert_eq!(p2, answers[1] as usize);
+    Ok((p1, p2))
 }