Complete 2023 day 6 part 1

2023/day6/src/main.rs

@@ -1,6 +1,6 @@
 const FILE_STR: &str = include_str!("input.txt");
 
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Copy, Clone)]
 struct RaceRecord {
     time: usize,
     distance: usize,
@@ -13,11 +13,108 @@ struct Races {
 
 impl Races {
     fn parse(records: &str) -> Self {
-        todo!();
+        let mut lines = records
+            .split('\n')
+            .map(|s| s.trim())
+            .filter(|s| !s.is_empty())
+            .map(|s| s.split(':'));
+        let times: Vec<_> = lines
+            .next()
+            .unwrap()
+            .nth(1)
+            .unwrap()
+            .split_whitespace()
+            .map(|n| n.trim())
+            .filter(|n| !n.is_empty())
+            .map(|n| n.parse::<usize>().unwrap())
+            .collect();
+
+        let distances: Vec<_> = lines
+            .next()
+            .unwrap()
+            .nth(1)
+            .unwrap()
+            .split_whitespace()
+            .map(|n| n.trim())
+            .filter(|n| !n.is_empty())
+            .map(|n| n.parse::<usize>().unwrap())
+            .collect();
+
+        let mut r = Races::default();
+        assert_eq!(times.len(), distances.len());
+        for i in 0..times.len() {
+            r.records.push(RaceRecord {
+                time: times[i],
+                distance: distances[i],
+            })
+        }
+
+        r
+    }
+
+    fn parse_single(records: &str) -> Self {
+        let mut lines = records
+            .split('\n')
+            .map(|s| s.trim())
+            .filter(|s| !s.is_empty())
+            .map(|s| s.split(':'));
+
+        let time = lines
+            .next()
+            .unwrap()
+            .nth(1)
+            .unwrap()
+            .replace(' ', "")
+            .parse::<usize>().unwrap();
+
+        let distance = lines
+            .next()
+            .unwrap()
+            .nth(1)
+            .unwrap()
+            .replace(' ', "")
+            .parse::<usize>().unwrap();
+
+        Races {
+            records: Vec::from([RaceRecord { time, distance}])
+        }
+    }
+
+    fn calculate_winning_counts(&self) -> Vec<usize> {
+        self.records
+            .iter()
+            .map(|r| winning_possibilities(*r).len())
+            .collect()
+    }
+
+    fn calculate_possible_win_product(&self) -> usize {
+        self.calculate_winning_counts()
+            .into_iter()
+            .reduce(|prev, curr| prev * curr)
+            .unwrap()
     }
 }
 
-fn part_one() {}
+fn winning_possibilities(race: RaceRecord) -> Vec<usize> {
+    let distance_calculation =
+        |race_length: usize, button_time: usize| button_time * (race_length - button_time);
+    let possible_range = 1..race.time;
+    possible_range
+        .filter_map(|button_time| {
+            let res = distance_calculation(race.time, button_time);
+            if res > race.distance {
+                Some(res)
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
+fn part_one() {
+    let records = Races::parse(FILE_STR);
+    println!("Part 1 Product of winning possibilitiesL {}", records.calculate_possible_win_product());
+}
 
 fn main() {
     part_one();
@@ -28,4 +125,16 @@ mod tests {
     const EXAMPLE_FILE_STR: &'static str = include_str!("example-input.txt");
 
     use super::*;
+
+    #[test]
+    fn test_calculate_winning_counts() {
+        let races = Races::parse(EXAMPLE_FILE_STR);
+        assert_eq!(Vec::from([4, 8, 9]), races.calculate_winning_counts());
+    }
+
+    #[test]
+    fn test_calculate_possible_win_product() {
+        let races = Races::parse(EXAMPLE_FILE_STR);
+        assert_eq!(288, races.calculate_possible_win_product());
+    }
 }