Some solutions to AOC 2020

1 files changed, 64 insertions, 0 deletions

diff --git a/2020/Rust/src/day2.rs b/2020/Rust/src/day2.rs
new file mode 100755
index 0000000..4785b3f
--- /dev/null
+++ b/2020/Rust/src/day2.rs
@@ -0,0 +1,64 @@
+struct Policy {
+    min: u32,
+    max: u32,
+    letter: char,
+    password: String,
+}
+
+impl From<&str> for Policy {
+    fn from(value: &str) -> Self {
+        let (left, right) = value.split_once(':').unwrap();
+        let (range, letter) = left.split_once(' ').unwrap();
+        let (min, max) = range.split_once("-").unwrap();
+        let password = right.trim_start().to_string();
+
+        Policy {
+            min: min.parse::<u32>().unwrap(),
+            max: max.parse::<u32>().unwrap(),
+            letter: letter.chars().next().unwrap(),
+            password,
+        }
+    }
+}
+
+fn check_policy(policy: &Policy) -> bool {
+    let count = policy.password.matches(policy.letter).count() as u32;
+    count >= policy.min && count <= policy.max
+}
+
+fn check_policy_part_two(policy: &Policy) -> bool {
+    let mut count = 0;
+    let policy_password = policy.password.as_bytes();
+    if policy_password[(policy.min - 1) as usize] == policy.letter as u8 {
+        count += 1;
+    }
+    if policy_password[(policy.max - 1) as usize] == policy.letter as u8 {
+        count += 1;
+    }
+    count == 1
+}
+
+fn solve_part_one(input: &str) -> usize {
+    input
+        .lines()
+        .map(|line| Policy::from(line))
+        .filter(|policy| check_policy(policy))
+        .count()
+}
+
+fn solve_part_two(input: &str) -> usize {
+    input
+        .lines()
+        .map(|line| Policy::from(line))
+        .filter(|policy| check_policy_part_two(policy))
+        .count()
+}
+
+fn main() {
+    let test = include_str!("../input/day_2.test");
+    let prod = include_str!("../input/day_2.prod");
+    println!("Test_1: {}", solve_part_one(test));
+    println!("Prod_1: {}", solve_part_one(prod));
+    println!("Test_2: {}", solve_part_two(test));
+    println!("Prod_2: {}", solve_part_two(prod));
+}