Day 8 part 2

2021/src/day8.rs

@@ -156,13 +156,10 @@ fn build_lookup(input: &str) -> Result<HashMap<String, &str>> {
     let one: HashSet<_> = map["1"].chars().collect();
     let four: HashSet<_> = map["4"].chars().collect();
 
-    //let seven_int: HashSet<_> = s.intersection(&seven).cloned().collect();
-    //let eight_int: HashSet<_> = s.intersection(&eight).cloned().collect();
-
     // 0, 6 or 9 have 6 segments:
-    // 0 is missing an intersection w/ 4
-    // 6 is missing an intersection w/ 1
-    // 9 is the left overs.
+    // 9 contains 1 and 4
+    // 0 intersects w/ 1 but not w/ 4
+    // 6 is the left overs.
     set.iter().filter(|s| s.len() == 6).for_each(|d| {
         let s: HashSet<_> = d.chars().collect();
         let one_int: HashSet<_> = s.intersection(&one).cloned().collect();
@@ -211,6 +208,7 @@ fn output(line: &str) -> Result<u64> {
     Ok(out
         .split(' ')
         .map(|s| {
+            // Sort letters in string before looking up.
             let mut s: Vec<_> = s.chars().collect();
             s.sort_unstable();
             let s: String = s.iter().collect();