Clean up D8

2019/08/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+itertools = "0.8.2"

2019/08/src/counter.rs

@@ -12,7 +12,13 @@ impl <T: Hash + Eq + Clone> Counter<T> {
         Self { values: HashMap::new() }
     }
 
-    pub fn add(&mut self, collection: &[T]) {
+    pub fn of<C: IntoIterator<Item=T>>(collection: C) -> Counter<T> {
+        let mut counter = Counter::new();
+        counter.add(collection);
+        counter
+    }
+
+    pub fn add<C: IntoIterator<Item=T>>(&mut self, collection: C) {
         for x in collection {
             self.values.insert(x.clone(), self.values.get(&x).unwrap_or(&0) + 1);
         }

2019/08/src/main.rs

@@ -1,42 +1,29 @@
 mod counter;
 use counter::Counter;
+use itertools::Itertools;
 use std::io::BufRead;
 
 const WIDTH: usize = 25;
 const HEIGHT: usize = 6;
 
 fn main() {
-    let input: Vec<_> = std::io::stdin()
-        .lock()
-        .lines()
-        .next()
-        .unwrap()
-        .unwrap()
-        .chars()
-        .collect();
-    let mut counters: Vec<_> = vec![];
-    let mut chunks = input.chunks(WIDTH).peekable();
+    let input = std::io::stdin().lock().lines().next().unwrap().unwrap();
+    let chunked = input.chars().chunks(HEIGHT * WIDTH);
+    let layers = chunked.into_iter();
     let mut img = vec!['2'; WIDTH * HEIGHT];
-    let mut cur_pos = (0..WIDTH * HEIGHT).cycle();
-    while chunks.peek().is_some() {
-        let mut counter = Counter::new();
-        for _ in 0..HEIGHT {
-            let next_chunk = chunks.next().unwrap();
-            for p in next_chunk {
-                let pos = cur_pos.next().unwrap();
-                if let Some(&'2') = img.get(pos) {
-                    img[pos] = *p;
-                }
+    let counters = layers.map(|layer| {
+        Counter::of(layer.enumerate().map(|(i, p)| {
+            if let Some(&'2') = img.get(i) {
+                img[i] = p
             }
-            counter.add(next_chunk);
-        }
-        counters.push(counter);
-    }
+            p
+        }))
+    });
 
-    let fewest_zeros = counters.into_iter().min_by_key(|c| c['0']).unwrap();
+    let fewest_zeros = counters.min_by_key(|c| c['0']).unwrap();
     println!("Part 1: {}", fewest_zeros['1'] * fewest_zeros['2']);
 
     for line in img.chunks(WIDTH) {
-        println!("{}", line.into_iter().collect::<String>().replace('0', " "));
+        println!("{}", line.iter().collect::<String>().replace('0', " "));
     }
 }