Add day2

day2/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day2"
+version = "0.1.0"

day2/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day2/src/main.rs

@@ -0,0 +1,52 @@
+fn parse(input: &str) -> Vec<Vec<u32>> {
+    input
+        .lines()
+        .map(|line| {
+            line.split_whitespace()
+                .map(|level| level.parse::<u32>().unwrap())
+                .collect()
+        })
+        .collect()
+}
+
+fn is_safe(report: &[u32]) -> bool {
+    let pairs: Vec<(u32, u32)> = report
+        .windows(2)
+        .map(|w| (*w.first().unwrap(), *w.get(1).unwrap()))
+        .collect();
+    pairs.iter().all(|(x, y)| x < y && x + 3 >= *y)
+        || pairs.iter().all(|(x, y)| x > y && *x <= y + 3)
+}
+
+fn part1(parsed_input: &[Vec<u32>]) -> u32 {
+    parsed_input
+        .iter()
+        .filter(|report| is_safe(report))
+        .count() as u32
+}
+
+fn part2(parsed_input: &[Vec<u32>]) -> u32 {
+    let mut res = 0;
+    for report in parsed_input {
+        if is_safe(report) {
+            res += 1;
+            continue;
+        }
+        for idx in 0..report.len() {
+            let mut modified_report = report.clone();
+            modified_report.remove(idx);
+            if is_safe(&modified_report) {
+                res += 1;
+                break;
+            }
+        }
+    }
+    res
+}
+
+fn main() {
+    let input = include_str!("../input.txt");
+    let parsed_input = parse(input);
+    println!("{}", part1(&parsed_input));
+    println!("{}", part2(&parsed_input));
+}