[2018][rust][2.0]

2018/rust/src/day_02.rs

@@ -0,0 +1,52 @@
+pub fn solve(input: &str) -> String {
+    let box_ids: Vec<_> = input.lines().map(BoxId::new).collect();
+
+    let two_count = box_ids.iter().filter(|&x| x.is_two()).count();
+    let three_count = box_ids.iter().filter(|&x| x.is_three()).count();
+
+    (two_count * three_count).to_string()
+}
+
+struct BoxId(String);
+
+impl BoxId {
+    fn new(s: &str) -> Self {
+        BoxId(s.into())
+    }
+
+    fn is_two(&self) -> bool {
+        self.is_n(2)
+    }
+
+    fn is_three(&self) -> bool {
+        self.is_n(3)
+    }
+
+    fn is_n(&self, n: usize) -> bool {
+        self.0
+            .chars()
+            .any(|x| self.0.chars().filter(|&y| x == y).count() == n)
+    }
+}
+
+#[test]
+fn test_is_two() {
+    assert_eq!(BoxId::new("abcdef").is_two(), false);
+    assert_eq!(BoxId::new("bababc").is_two(), true);
+    assert_eq!(BoxId::new("abbcde").is_two(), true);
+    assert_eq!(BoxId::new("abcccd").is_two(), false);
+    assert_eq!(BoxId::new("aabcdd").is_two(), true);
+    assert_eq!(BoxId::new("abcdee").is_two(), true);
+    assert_eq!(BoxId::new("ababab").is_two(), false);
+}
+
+#[test]
+fn test_is_three() {
+    assert_eq!(BoxId::new("abcdef").is_three(), false);
+    assert_eq!(BoxId::new("bababc").is_three(), true);
+    assert_eq!(BoxId::new("abbcde").is_three(), false);
+    assert_eq!(BoxId::new("abcccd").is_three(), true);
+    assert_eq!(BoxId::new("aabcdd").is_three(), false);
+    assert_eq!(BoxId::new("abcdee").is_three(), false);
+    assert_eq!(BoxId::new("ababab").is_three(), true);
+}

2018/rust/src/main.rs

@@ -1,11 +1,12 @@
 use std::io::{self, Read};
 
 mod day_01;
+mod day_02;
 
 fn main() {
     let mut input = String::new();
     io::stdin().read_to_string(&mut input).unwrap();
 
-    let output = day_01::solve_1(&input, "\n");
+    let output = day_02::solve(&input);
     println!("{}", output);
 }