Complete Day 5

day_05/src/main.rs

@@ -6,6 +6,15 @@ use std::{
     io::{BufReader, prelude::*},
 };
 
+fn accumulate_middle_pages(page_updates: Vec<Vec<i64>>) -> i64 {
+    let mut accumulator = 0;
+    for update in page_updates {
+        let middle_page = update[update.len() / 2];
+        accumulator += middle_page;
+    }
+    accumulator
+}
+
 fn main() -> Result<(), Box<dyn Error>> {
     // Handle command input
     let args: Vec<String> = env::args().collect();
@@ -78,13 +87,36 @@ fn main() -> Result<(), Box<dyn Error>> {
         }
     }
 
-    let mut accumulator = 0;
-    for update in valid_page_updates {
-        let middle_page = update[update.len() / 2];
-        accumulator += middle_page;
+    let accumulator = accumulate_middle_pages(valid_page_updates);
+    println!("Sum of middle pages from valid updates: {}", accumulator);
+
+    let mut fixed_updates = Vec::new();
+    for page_update in invalid_page_updates {
+        let mut reordered_page_update: Vec<i64> = Vec::new();
+        for page in page_update {
+            let inserted = if let Some(rule_set) = page_rules.get(&page) {
+                let mut inserted = false;
+                for (i, reordered_page) in reordered_page_update.iter().enumerate() {
+                    if rule_set.contains(reordered_page) {
+                        reordered_page_update.insert(i, page);
+                        inserted = true;
+                        break;
+                    }
+                }
+                inserted
+            } else {
+                reordered_page_update.push(page);
+                true
+            };
+            if !inserted {
+                reordered_page_update.push(page);
+            }
+        }
+        fixed_updates.push(reordered_page_update);
     }
 
-    println!("Sum of middle pages from valid updates: {}", accumulator);
+    let accumulator = accumulate_middle_pages(fixed_updates);
+    println!("Sum of middle pages from fixed updates: {}", accumulator);
 
     Ok(())
 }