2015/03

2015/03/src/main.rs

@@ -0,0 +1,76 @@
+use std::io::{self, Read};
+use std::collections::HashMap;
+
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin().read_to_string(&mut input).unwrap();
+
+    let count = process(&input, 2);
+
+    println!("count={}", count);
+}
+
+fn process(input: &str, versions: usize) -> usize {
+    let mut houses: HashMap<(i32, i32), i32> = HashMap::new();
+
+    houses.insert((0, 0), versions as i32);
+
+    let mut index = (0..versions).cycle();
+    let mut pos = vec![(0, 0); versions];
+
+    for step in input.chars() {
+        let i = index.next().unwrap();
+
+        pos[i] = match step {
+            '>' => (pos[i].0 + 1, pos[i].1),
+            '<' => (pos[i].0 - 1, pos[i].1),
+            '^' => (pos[i].0, pos[i].1 + 1),
+            'v' => (pos[i].0, pos[i].1 - 1),
+            _   => pos[i],
+        };
+
+        let count = houses.entry(pos[i]).or_insert(0);
+
+        *count += 1;
+    }
+
+    houses.len()
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::process;
+
+    #[test]
+    fn example_01() {
+        assert_eq!(2, process(">", 1));
+    }
+
+    #[test]
+    fn example_02() {
+        assert_eq!(4, process("^>v<", 1));
+    }
+
+    #[test]
+    fn example_03() {
+        assert_eq!(2, process("^v^v^v^v^v", 1));
+    }
+
+    #[test]
+    fn example_04() {
+        assert_eq!(3, process("^v", 2));
+    }
+
+    #[test]
+    fn example_05() {
+        assert_eq!(3, process("^>v<", 2));
+    }
+
+    #[test]
+    fn example_06() {
+        assert_eq!(11, process("^v^v^v^v^v", 2));
+    }
+}