feat: Completed day 7 BACK UP TO DATE!

src/solutions/day06.rs

@@ -61,7 +61,6 @@ impl Solution for Day06 {
                 _ => unreachable!(),
             };
 
-            println!("Problem: {:?} {}, Result: {}", numbers, op, result);
             grand_total += result;
         }
         Ok(Box::new(grand_total))

src/solutions/day07.rs

@@ -5,16 +5,18 @@ pub struct Day07 {}
 impl Solution for Day07 {
     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"))
+        let (p1, _p2) = self.solve_paths(input);
+        Ok(Box::new(p1))
     }
 
     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"))
+        let (_p1, p2) = self.solve_paths(input);
+        Ok(Box::new(p2))
     }
 
     fn get_day(&self) -> u8 {
@@ -22,7 +24,43 @@ impl Solution for Day07 {
     }
 }
 
-impl Day07 {}
+impl Day07 {
+    fn solve_paths(&self, input: &Vec<String>) -> (usize, usize) {
+        let lines: Vec<_> = input.iter().map(String::as_bytes).collect();
+        let width = lines[0].len();
+        let start = lines[0].iter().position(|&b| b == b'S').unwrap();
+
+        let mut splits = 0;
+        let mut current = vec![0; width];
+        let mut next = vec![0; width];
+
+        current[start] = 1;
+
+        for row in lines {
+            for (i, &count) in current.iter().enumerate() {
+                if count > 0 {
+                    if row[i] == b'^' {
+                        splits += 1;
+
+                        if i > 0 {
+                            next[i - 1] += count;
+                        }
+                        if i < width - 1 {
+                            next[i + 1] += count;
+                        }
+                    } else {
+                        next[i] += count;
+                    }
+                }
+            }
+
+            (current, next) = (next, current);
+            next.fill(0);
+        }
+
+        (splits, current.iter().sum())
+    }
+}
 
 /// Test from puzzle input
 #[cfg(test)]
@@ -44,7 +82,7 @@ mod test {
             .unwrap()
             .to_string();
 
-        assert_eq!(answer, "Ready");
+        assert_eq!(answer, "21");
     }
 
     #[test]
@@ -61,6 +99,6 @@ mod test {
             .unwrap()
             .to_string();
 
-        assert_eq!(answer, "Ready");
+        assert_eq!(answer, "40");
     }
 }