feat: Completed Day 1 YAY

src/solutions/day01.rs

@@ -5,16 +5,16 @@ pub struct Day01 {}
 impl Solution for Day01 {
     fn part1(
         &self,
-        _input: &mut Vec<String>,
+        input: &mut Vec<String>,
     ) -> Result<Box<dyn std::fmt::Display>, Box<dyn std::error::Error>> {
-        Ok(Box::new("Ready"))
+        Ok(Box::new(Day01::count_zeros(input, false)))
     }
 
     fn part2(
         &self,
-        _input: &mut Vec<String>,
+        input: &mut Vec<String>,
     ) -> Result<Box<dyn std::fmt::Display>, Box<dyn std::error::Error>> {
-        Ok(Box::new("Ready"))
+        Ok(Box::new(Day01::count_zeros(input, true)))
     }
 
     fn get_day(&self) -> u8 {
@@ -22,7 +22,59 @@ impl Solution for Day01 {
     }
 }
 
-impl Day01 {}
+impl Day01 {
+    fn count_zeros(input: &Vec<String>, count_passing: bool) -> usize {
+        // Dial starts at 50
+        let mut pos: i64 = 50;
+        let mut zeros: usize = 0;
+
+        for line in input {
+            let line = line.trim();
+            if line.is_empty() {
+                continue;
+            }
+
+            let mut chars = line.chars();
+            let dir = chars.next().expect("empty line");
+            let dist_str: String = chars.collect::<String>().trim().to_string();
+            let dist: i64 = dist_str.parse().expect("invalid distance number");
+
+            // Count any time that the dial moves past 0.
+            if count_passing {
+                // Count all zeros passed during the move
+                let step = match dir {
+                    'L' | 'l' => -1,
+                    'R' | 'r' => 1,
+                    _ => panic!("invalid direction (must start with L or R): {}", dir),
+                };
+
+                for _ in 0..dist {
+                    pos = (pos + step).rem_euclid(100);
+                    if pos == 0 {
+                        zeros += 1;
+                    }
+                }
+                continue;
+            }
+
+            // Move directly to the new position
+            match dir {
+                'L' | 'l' => {
+                    pos = (pos - dist).rem_euclid(100);
+                }
+                'R' | 'r' => {
+                    pos = (pos + dist).rem_euclid(100);
+                }
+                _ => panic!("invalid direction (must start with L or R): {}", dir),
+            }
+
+            if pos == 0 {
+                zeros += 1;
+            }
+        }
+        zeros
+    }
+}
 
 /// Test from puzzle input
 #[cfg(test)]
@@ -44,7 +96,7 @@ mod test {
             .unwrap()
             .to_string();
 
-        assert_eq!(answer, "Ready");
+        assert_eq!(answer, "3");
     }
 
     #[test]
@@ -61,6 +113,6 @@ mod test {
             .unwrap()
             .to_string();
 
-        assert_eq!(answer, "Ready");
+        assert_eq!(answer, "6");
     }
 }