solution: day3

src/bin/03.rs

@@ -0,0 +1,66 @@
+use std::collections::HashSet;
+
+use itertools::Itertools;
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut visited = HashSet::with_capacity(input.len());
+    visited.insert((0,0));
+    let mut x = 0;
+    let mut y = 0;
+    for direction in input.trim().chars() {
+        match direction {
+            '>' => x += 1,
+            '<' => x -= 1,
+            '^' => y += 1,
+            'v' => y -= 1,
+            _ => panic!("oops")
+        };
+        visited.insert((x, y));
+    };
+    Some(visited.len() as u32)
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    let mut visited = HashSet::with_capacity(input.len());
+    visited.insert((0,0));
+    let (mut x1, mut y1, mut x2, mut y2) = (0, 0, 0, 0);
+    for (santa, robot) in input.trim().chars().tuple_windows().step_by(2) {
+        match santa {
+            '>' => x1 += 1,
+            '<' => x1 -= 1,
+            '^' => y1 += 1,
+            'v' => y1 -= 1,
+            _ => panic!("oops")
+        };
+        visited.insert((x1, y1));
+        match robot {
+            '>' => x2 += 1,
+            '<' => x2 -= 1,
+            '^' => y2 += 1,
+            'v' => y2 -= 1,
+            _ => panic!("oops")
+        };
+        visited.insert((x2, y2));
+    };
+    Some(visited.len() as u32)
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 3);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        // let input = aoc::read_file("test_inputs", 3);
+        let input = "^v^v^v^v^v";
+        assert_eq!(part_one(&input), Some(2));
+    }
+    #[test]
+    fn test_part_two() {
+        // let input = aoc::read_file("test_inputs", 3);
+        let input = "^v^v^v^v^v";
+        assert_eq!(part_two(&input), Some(11));
+    }
+}