day two, part one

day-2/Cargo.toml

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+[package]
+name = "day-2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day-2/src/main.rs

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+use std::fs;
+
+fn is_safe(report: Vec<i32>) -> bool {
+    let mut order = 0;
+
+    for index in 1..report.len() {
+        let diff = report[index].checked_sub(report[index - 1]).unwrap();
+        let abs_diff = diff.abs();
+
+        if abs_diff < 1 || abs_diff > 3 {
+            return false;
+        };
+
+        if order == 0 {
+            order = diff / abs_diff
+        } else if order != diff / abs_diff {
+            return false;
+        }
+    }
+    true
+}
+
+fn solution(s: &str) {
+    let mut safe_reports = 0;
+    for line in s.lines() {
+        if is_safe(
+            line.split_whitespace()
+                .map(|val| val.parse::<i32>().unwrap())
+                .collect(),
+        ) {
+            safe_reports += 1;
+        }
+    }
+    println!("There are {safe_reports} Safe reports!");
+}
+
+fn main() {
+    let s = fs::read_to_string("levels.txt").unwrap();
+    solution(&s);
+}