2017/08-09

2017/09/src/main.rs

@@ -0,0 +1,105 @@
+use std::io::{self, Read};
+
+
+#[derive(Clone, Copy)]
+enum State {
+    Group,
+    Garbage,
+    Ignore,
+}
+
+
+fn scan(input: &str) -> (usize, usize) {
+    let mut score = 0;
+    let mut garbage = 0;
+
+    let mut indendation = 0;
+
+    let mut states = Vec::new();
+
+    for ch in input.chars() {
+        let state = *states.last().unwrap_or(&State::Group);
+
+        match (state, ch) {
+            // Group
+            (State::Group, '{') => {
+                indendation += 1;
+            }
+            (State::Group, '}') => {
+                score += indendation;
+                indendation -= 1;
+
+                states.pop();
+            }
+            (State::Group, '<') => {
+                states.push(State::Garbage);
+            }
+            (State::Group, '!') => {
+                states.push(State::Ignore);
+            }
+
+            // Garbage
+            (State::Garbage, '>') => {
+                states.pop();
+            }
+            (State::Garbage, '!') => {
+                states.push(State::Ignore);
+            }
+            (State::Garbage, _) => {
+                garbage += 1;
+            }
+
+            // Ignore
+            (State::Ignore, _) => {
+                states.pop();
+            }
+
+            _ => (),
+        }
+    }
+
+    (score, garbage)
+}
+
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin()
+        .read_to_string(&mut input)
+        .expect("faild to read input");
+
+    let (score, garbage) = scan(&input);
+
+    println!("part_one={}", score);
+    println!("part_two={}", garbage);
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_score() {
+        assert_eq!(scan("{}"), (1, 0));
+        assert_eq!(scan("{{{}}}"), (6, 0));
+        assert_eq!(scan("{{},{}}"), (5, 0));
+        assert_eq!(scan("{{{},{},{{}}}}"), (16, 0));
+        assert_eq!(scan("{<a>,<a>,<a>,<a>}"), (1, 4));
+        assert_eq!(scan("{{<ab>},{<ab>},{<ab>},{<ab>}}"), (9, 8));
+        assert_eq!(scan("{{<!!>},{<!!>},{<!!>},{<!!>}}"), (9, 0));
+        assert_eq!(scan("{{<a!>},{<a!>},{<a!>},{<ab>}}"), (3, 17));
+    }
+
+    #[test]
+    fn test_garbage() {
+        assert_eq!(scan("<>"), (0, 0));
+        assert_eq!(scan("<random characters>"), (0, 17));
+        assert_eq!(scan("<<<<>"), (0, 3));
+        assert_eq!(scan("<{!>}>"), (0, 2));
+        assert_eq!(scan("<!!>"), (0, 0));
+        assert_eq!(scan("<!!!>>"), (0, 0));
+        assert_eq!(scan(r#"<{o"i!a,<{i<a>"#), (0, 10));
+    }
+}