feat: solve 02/2024 part 1

readme.md

@@ -9,9 +9,10 @@
 
 # 2024
 
-| Day                                                           | Solved | Part 1 time (ms) | Part 2 time (ms) |
-|---------------------------------------------------------------|:------:|-----------------:|-----------------:|
-| [Day 1: Historian Hysteria ](src/solutions/year2024/day01.rs) |   ⭐⭐   |            0.221 |            0.219 |
+| Day                                                          | Solved | Part 1 time (ms) | Part 2 time (ms) |
+|--------------------------------------------------------------|:------:|-----------------:|-----------------:|
+| [Day 1: Historian Hysteria](src/solutions/year2024/day01.rs) |   ⭐⭐   |            0.221 |            0.219 |
+| [Day 2: Red-Nosed Reports](src/solutions/year2024/day02.rs)  |   ⭐    |            0.508 |                  |
 
 # 2023
 

src/solutions/mod.rs

@@ -15,6 +15,7 @@ pub fn solution(day: DayNumber, year: Year) -> Box<dyn Solution> {
     match year {
         Year::Year2024 => match i {
             1 => Box::new(year2024::day01::Day01),
+            2 => Box::new(year2024::day02::Day02),
             _ => panic!("Day not exist"),
         },
         Year::Year2023 => match i {

src/solutions/year2024/day02.rs

@@ -1,26 +1,102 @@
+use crate::solutions::year2024::day02::State::{Decreasing, Equals, Increasing};
 use crate::solutions::Solution;
 
 pub struct Day02;
 
 impl Solution for Day02 {
-    fn part_one(&self, _input: &str) -> String {
-        String::new()
+    fn part_one(&self, input: &str) -> String {
+        let input = self.parse(input);
+
+        input
+            .iter()
+            .filter(|report| {
+                let mut state: Option<State> = None;
+
+                for i in 0..report.len() - 1 {
+                    let first = report.get(i).unwrap();
+                    let second = report.get(i + 1).unwrap();
+
+                    if (first - second).abs() > 3 {
+                        return false;
+                    }
+
+                    let current_state = if first < second {
+                        Increasing
+                    } else if first > second {
+                        Decreasing
+                    } else if first == second {
+                        Equals
+                    } else {
+                        unreachable!()
+                    };
+
+                    if let Some(inner_state) = state {
+                        if inner_state == Equals {
+                            return false;
+                        }
+                        if inner_state != current_state {
+                            return false;
+                        }
+                    } else {
+                        state = Some(current_state);
+                    }
+                }
+
+                true
+            })
+            .count()
+            .to_string()
     }
 
     fn part_two(&self, _input: &str) -> String {
         String::new()
     }
 }
 
+impl Day02 {
+    fn parse(&self, input: &str) -> Vec<Vec<i32>> {
+        input
+            .lines()
+            .map(|line| {
+                line.split_terminator(" ")
+                    .map(|n| n.parse::<i32>().unwrap())
+                    .collect::<Vec<i32>>()
+            })
+            .collect()
+    }
+}
+
+#[derive(Copy, Clone, PartialEq)]
+enum State {
+    Increasing,
+    Decreasing,
+    Equals,
+}
+
 #[cfg(test)]
 mod tests {
     use crate::solutions::year2024::day02::Day02;
     use crate::solutions::Solution;
 
-    const EXAMPLE: &str = r#""#;
+    const EXAMPLE: &str = r#"7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9"#;
 
     #[test]
     fn part_one_example_test() {
-        assert_eq!("", Day02.part_one(EXAMPLE));
+        assert_eq!("2", Day02.part_one(EXAMPLE));
+    }
+
+    #[test]
+    fn part_one_with_equals_test() {
+        assert_eq!("0", Day02.part_one("2 2 2"));
+        assert_eq!("0", Day02.part_one("2 2 1"));
+        assert_eq!("0", Day02.part_one("2 2 3"));
+        assert_eq!("0", Day02.part_one("1 2 2"));
+        assert_eq!("0", Day02.part_one("2 2 2"));
+        assert_eq!("0", Day02.part_one("3 2 2"));
     }
 }