02 (WIP)

day_02/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day_02"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

day_02/example.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

day_02/src/main.rs

@@ -0,0 +1,50 @@
+use std::fs::read_to_string;
+
+#[cfg(debug_assertions)]
+const INPUT: &str = "example.txt";
+#[cfg(not(debug_assertions))]
+const INPUT: &str = "input.txt";
+
+fn main() {
+    let mut count_safe = 0;
+    read_to_string(INPUT).unwrap().lines().for_each(|line| {
+        let data: Vec<_> = line
+            .split_whitespace()
+            .map(|item| item.parse::<isize>().unwrap())
+            .collect();
+
+        let mut diffs = vec![];
+
+        for first in 0..data.len() - 1 {
+            let second = first + 1;
+            diffs.push(data[second] - data[first]);
+        }
+
+        for diff in &diffs {
+            if is_unsafe(*diff) {
+                return;
+            }
+        }
+
+        if all_same_sign(&diffs) {
+            count_safe += 1;
+        }
+    });
+
+    println!("{count_safe}");
+}
+
+fn all_same_sign(diffs: &[isize]) -> bool {
+    let first = diffs[0].signum();
+    for diff in diffs {
+        if diff.signum() != first {
+            return false;
+        }
+    }
+    true
+}
+
+fn is_unsafe(mut diff: isize) -> bool {
+    diff = diff.abs();
+    !(1..=3).contains(&diff)
+}