From a141de6ff47cd3fe7db921f9529b4abdc4271cf6 Mon Sep 17 00:00:00 2001
From: _tud <98935832+UnderscoreTud@users.noreply.github.com>
Date: Mon, 2 Dec 2024 15:11:24 +0300
Subject: [PATCH] Day 2

---
 data/examples/02.txt |  6 ++++
 src/bin/02.rs        | 70 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 data/examples/02.txt
 create mode 100644 src/bin/02.rs

diff --git a/data/examples/02.txt b/data/examples/02.txt
new file mode 100644
index 0000000..82cd679
--- /dev/null
+++ b/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
\ No newline at end of file
diff --git a/src/bin/02.rs b/src/bin/02.rs
new file mode 100644
index 0000000..bad38fc
--- /dev/null
+++ b/src/bin/02.rs
@@ -0,0 +1,70 @@
+advent_of_code::solution!(2);
+
+fn is_safe(data: &Vec<u32>) -> bool {
+    let mut previous_direction = None;
+    for i in 0..(data.len() - 1) {
+        let diff = data[i].abs_diff(data[i + 1]);
+        if diff > 3 {
+            return false;
+        }
+        let direction = data[i].cmp(&data[i + 1]);
+        match previous_direction {
+            Some(previous_direction) => if previous_direction != direction {
+                return false;
+            },
+            None => previous_direction = Some(direction)
+        }
+    }
+    true
+}
+
+fn is_safe_lenient(data: &Vec<u32>) -> bool {
+    if is_safe(data) {
+        return true;
+    }
+    for i in 0..data.len() {
+        let mut modified_data = data.clone();
+        modified_data.remove(i);
+        if is_safe(&modified_data) {
+            return true
+        }
+    }
+    false
+}
+
+fn count_safe_reports<P>(input: &str, predicate: P) -> u32
+where
+    P: FnMut(&Vec<u32>) -> bool
+{
+    input.lines()
+        .map(|line| line.split_whitespace()
+            .map(|number| number.parse::<u32>().unwrap())
+            .collect::<Vec<u32>>())
+        .filter(predicate)
+        .count() as u32
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    Some(count_safe_reports(input, is_safe))
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    Some(count_safe_reports(input, is_safe_lenient))
+}
+
+#[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));
+    }
+}