feat: add day 2

README.md

@@ -18,8 +18,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | Day | Part 1 | Part 2 |
 | :---: | :---: | :---:  |
 | [Day 1](./src/bin/01.rs) | `72.0µs` | `76.8µs` |
+| [Day 2](./src/bin/02.rs) | `333.6µs` | `642.1µs` |
 
-**Total: 0.15ms**
+**Total: 1.12ms**
 <!--- benchmarking table --->
 
 ---

data/examples/02.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

src/bin/02.rs

@@ -0,0 +1,88 @@
+advent_of_code::solution!(2);
+
+use std::cmp::Ordering;
+
+fn validate_input_p1(input: &Vec<u32>) -> bool {
+    input
+        .iter()
+        .fold(
+            (true, 0, None),
+            |(is_good, last, ord): (bool, u32, Option<Ordering>), cur: &u32| match (
+                is_good, last, cur, ord,
+            ) {
+                (false, _, _, _) => (false, 0, None),
+                (_, 0, cur, None) => (true, *cur, None),
+                (_, last, cur, None) if last.abs_diff(*cur) < 4 => {
+                    (true, *cur, Some(last.cmp(cur)))
+                }
+                (_, last, cur, Some(cmp)) if last.abs_diff(*cur) < 4 && last.cmp(cur) == cmp => {
+                    (true, *cur, Some(cmp))
+                }
+                _ => (false, 0, None),
+            },
+        )
+        .0
+}
+
+fn validate_input_p2(input: &Vec<u32>) -> bool {
+    if validate_input_p1(input) {
+        return true;
+    }
+
+    for i in 0..input.len() {
+        let mut input2 = input.clone();
+        input2.remove(i);
+        if validate_input_p1(&input2) {
+            return true;
+        }
+    }
+
+    false
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    input
+        .strip_suffix("\n")
+        .unwrap_or(input)
+        .lines()
+        .map(|s| {
+            s.split_whitespace()
+                .map(|nb| nb.parse::<u32>().expect("parsing failed"))
+                .collect::<Vec<u32>>()
+        })
+        .filter(validate_input_p1)
+        .count()
+        .into()
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    input
+        .strip_suffix("\n")
+        .unwrap_or(input)
+        .lines()
+        .map(|s| {
+            s.split_whitespace()
+                .map(|nb| nb.parse::<u32>().expect("parsing failed"))
+                .collect::<Vec<u32>>()
+        })
+        .filter(validate_input_p2)
+        .count()
+        .into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(2));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(4));
+    }
+}