1 files changed, 30 insertions, 41 deletions
diff --git a/day01b/src/main.rs b/day01b/src/main.rs
index 4c880c4..1f93202 100644
--- a/day01b/src/main.rs
+++ b/day01b/src/main.rs
@@ -16,6 +16,7 @@
 /// Find the top three Elves carrying the most Calories.  How many Calories are those Elves carrying
 /// in total?
 use clap::Parser;
+use itertools::Itertools;
 
 use std::collections::BinaryHeap;
 use std::fs::File;
@@ -54,53 +55,41 @@ fn main() {
     let args = Cli::parse();
 
     let file = File::open(&args.file).unwrap();
-    let mut reader = BufReader::new(file);
+    let reader = BufReader::new(file);
 
     let mut heap = BinaryHeap::new();
-    let mut line = String::new();
-    let mut calorie_count = CalorieCount {
-        elf: 1,
-        calories: 0,
-    };
-    while let Ok(bytes) = reader.read_line(&mut line) {
-        // EOF
-        if bytes == 0 {
-            heap.push(calorie_count);
-            break;
-        }
-
-        // Newlines
-        let tline = line.trim();
-        if tline.is_empty() {
-            // Push onto the binary heap
-            heap.push(calorie_count);
-            calorie_count.calories = 0;
-            calorie_count.elf += 1;
-            continue;
-        }
-
-        // Parse the calories
-        let calories = tline.parse::<usize>().unwrap();
-
-        // Accumulate the calorie count for this elf
-        calorie_count.calories += calories;
-
-        // Clear the line for the next iteration
-        line.clear();
-    }
-
-    // Find the elf carrying the most calories
+    let _ = reader
+        .lines()
+        .map(|l| l.unwrap())
+        .peekable()
+        .batching(|it| {
+            if it.peek().is_none() {
+                return None;
+            }
+            Some(
+                it.take_while(|l| !l.is_empty())
+                    .map(|w| w.parse::<usize>().unwrap())
+                    .collect::<Vec<usize>>(),
+            )
+        })
+        .zip(1..)
+        .scan(&mut heap, |heap, (batch, elf)| {
+            heap.push(CalorieCount {
+                elf,
+                calories: batch.iter().sum(),
+            });
+            match heap.peek() {
+                None => None,
+                Some(_) => Some(()),
+            }
+        })
+        .last();
+
+    // Find the top 3 elves carrying the most calories
     let res = heap
         .into_iter_sorted()
         .inspect(|x| println!("calories={:6} elf={}", x.calories, x.elf))
         .take(3)
         .fold(0usize, |acc, x| acc + x.calories);
     println!("The top 3 elves are carry {res} calories");
-
-    let mut cals = include_str!("../examples/input.txt")
-        .split("\n\n")
-        .map(|e| e.lines().map(|c| c.parse::<u32>().unwrap()).sum())
-        .collect::<Vec<u32>>();
-    cals.sort_unstable();
-    println!("{}", cals.into_iter().rev().take(3).sum::<u32>());
 }