Add D8P1 in Rust

2019/08/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "day08"
+version = "0.1.0"
+authors = ["kageru <kageru@encode.moe>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2019/08/src/counter.rs

@@ -0,0 +1,28 @@
+use std::collections::HashMap;
+use std::ops::Index;
+use std::hash::Hash;
+
+#[derive(Debug)]
+pub struct Counter<T: Hash + Eq + Clone> {
+    values: HashMap<T, usize>
+}
+
+impl <T: Hash + Eq + Clone> Counter<T> {
+    pub fn new() -> Self {
+        Self { values: HashMap::new() }
+    }
+
+    pub fn add(&mut self, collection: &[T]) {
+        for x in collection {
+            self.values.insert(x.clone(), self.values.get(&x).unwrap_or(&0) + 1);
+        }
+    }
+}
+
+impl <T: Hash + Eq + Clone> Index<T> for Counter<T> {
+    type Output = usize;
+
+    fn index(&self, idx: T) -> &usize {
+        self.values.get(&idx).unwrap_or(&0)
+    }
+}

2019/08/src/main.rs

@@ -0,0 +1,22 @@
+mod counter;
+use counter::Counter;
+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();
+    while chunks.peek().is_some() {
+        let mut counter = Counter::new();
+        for _ in 0..HEIGHT {
+            counter.add(chunks.next().unwrap());
+        }
+        counters.push(counter);
+    }
+    
+    let fewest_zeros = counters.into_iter().min_by_key(|c| c['0']).unwrap();
+    println!("{:?}", fewest_zeros['1'] * fewest_zeros['2']);
+}