🚧 Day 2: Failed attempt at solving part 2

README.md

@@ -4,7 +4,7 @@
 [![Language: Rust](https://img.shields.io/badge/Language-Rust-orange.svg?style=flat-square)](https://en.wikipedia.org/wiki/Rust_(programming_language))
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg?style=flat-square)](https://mit-license.org/)
 ![Days completed](https://img.shields.io/badge/Days%20completed-1-red?style=flat-square)
-![Stars](https://img.shields.io/badge/Stars-2-yellow?style=flat-square)
+![Stars](https://img.shields.io/badge/Stars-3-yellow?style=flat-square)
 
 > ⚠️ This README is copied from my previous years solution. It is not fully adopted to 2024 yet.
 

src/days/d02.rs

@@ -2,31 +2,107 @@ use super::{Answer, Day, DayImpl};
 
 const CURRENT_DAY: u8 = 2;
 
-type Data = Vec<u64>;
+pub enum Direction {
+    Increasing,
+    Decreasing,
+}
+
+#[derive(Clone, Debug)]
+pub struct Report(Vec<i8>);
+
+impl Report {
+    pub fn is_safe(&self, mut tolerance: usize) -> bool {
+        let mut direction = None;
+        let mut skip = false;
+
+        for i in 1..self.0.len() {
+            if skip {
+                skip = false;
+                continue;
+            }
+
+            if !Self::safe_comparison(self.0[i - 1], self.0[i], &mut direction) {
+                if tolerance > 0 && i > 1 {
+                    tolerance -= 1;
+                    if !Self::safe_comparison(self.0[i - 2], self.0[i], &mut direction) {
+                        skip = true;
+                        continue;
+                    }
+                }
+
+                return false;
+            }
+        }
+
+        true
+    }
+
+    fn safe_comparison(a: i8, b: i8, direction: &mut Option<Direction>) -> bool {
+        match (b - a, &direction) {
+            /* Over limits */
+            (..=-4 | 4.., _) => return false,
+
+            /* Decide on direction */
+            (..=-1, None) => *direction = Some(Direction::Decreasing),
+            (1.., None) => *direction = Some(Direction::Increasing),
+
+            /* Wrong Direction */
+            (1.., Some(Direction::Decreasing)) => return false,
+            (..=-1, Some(Direction::Increasing)) => return false,
+
+            /* No Change */
+            (0, _) => return false,
+            _ => {}
+        }
+
+        return true;
+    }
+}
+
+impl From<&str> for Report {
+    fn from(value: &str) -> Self {
+        Self(
+            value
+                .split_whitespace()
+                .map(|v| v.parse::<i8>().expect("error while parsing input."))
+                .collect(),
+        )
+    }
+}
+
+type Data = Vec<Report>;
 impl DayImpl<Data> for Day<CURRENT_DAY> {
     fn init_test() -> (Self, Data) {
         Self::init(include_str!("test_inputs/test02.txt"))
     }
 
     fn expected_results() -> (Answer, Answer) {
-        (Answer::Number(0), Answer::Number(0))
+        (Answer::Number(2), Answer::Number(4))
     }
 
     fn init(input: &str) -> (Self, Data) {
-        (
-            Self {},
-            input
-                .lines()
-                .map(|v| v.parse::<u64>().expect("error while parsing input."))
-                .collect(),
-        )
+        (Self {}, input.lines().map(|l| l.into()).collect())
     }
 
     fn one(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        let mut safe_count = 0;
+        for report in data {
+            if report.is_safe(0) {
+                safe_count += 1;
+            }
+        }
+
+        return Answer::Number(safe_count);
     }
 
     fn two(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        let mut safe_count = 0;
+        for report in data {
+            if report.is_safe(1) {
+                safe_count += 1;
+            }
+        }
+
+        return Answer::Number(safe_count);
     }
 }

src/days/test_inputs/test02.txt

@@ -0,0 +1,6 @@
+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