day 22 task 1

src/main.rs

@@ -1,5 +1,5 @@
 mod tasks;
 
 fn main() {
-    tasks::day18::run();
+    tasks::day22::run();
 }

src/tasks/day18.rs

@@ -80,6 +80,7 @@ struct StateSummaryDist(Pos, HashSet<char>, usize);
 #[derive(PartialEq, Eq, Clone)]
 struct Map(Vec<Vec<char>>);
 
+#[allow(dead_code)]
 impl Map {
     fn coordinate_of(&self, symbol: char) -> Vec<Pos> {
         self.0

src/tasks/day22.rs

@@ -0,0 +1,57 @@
+use std::collections::VecDeque;
+
+#[allow(dead_code)]
+pub fn run() {
+    let input = std::fs::read_to_string("input/day22.txt").unwrap();
+    task1(input);
+}
+
+type Deck = VecDeque<u16>;
+
+fn task1(input: String) {
+    let deck_size = 10_007;
+    let mut deck: Deck = (0..deck_size).collect();
+    for line in input.lines() {
+        if line.starts_with("deal into new stack") {
+            deck = into_new_stack(deck);
+        } else if line.starts_with("cut") {
+            let s = line.split("cut ").collect::<Vec<_>>();
+            let n = s[1].parse::<i32>().unwrap();
+            deck = cut_cards(deck, n);
+        } else if line.starts_with("deal with increment") {
+            let s = line.split("deal with increment ").collect::<Vec<_>>();
+            let n = s[1].parse::<usize>().unwrap();
+            deck = deal_with_increment(deck, n);
+        }
+    }
+
+    let pos_2019 = deck
+        .iter()
+        .enumerate()
+        .find_map(|(i, card)| if *card == 2019 { Some(i) } else { None });
+
+    println!("Result: {:?}", pos_2019);
+}
+
+fn into_new_stack(deck: Deck) -> Deck {
+    deck.into_iter().rev().collect()
+}
+
+fn cut_cards(mut deck: Deck, n: i32) -> Deck {
+    if n > 0 {
+        deck.rotate_left(n as usize);
+    } else {
+        deck.rotate_right(-n as usize);
+    };
+    deck
+}
+
+fn deal_with_increment(deck: Deck, n: usize) -> Deck {
+    let mut new = vec![0; deck.len()];
+    let mut index = 0;
+    for card in deck.into_iter() {
+        new[index] = card;
+        index = (index + n) % new.len();
+    }
+    new.into_iter().collect()
+}

src/tasks/day24.rs

@@ -325,6 +325,7 @@ impl Pos {
     }
 }
 
+#[allow(unused)]
 mod test {
     use super::Field;
     #[test]

src/tasks/mod.rs

@@ -16,4 +16,5 @@ pub mod day16;
 pub mod day17;
 pub mod day18;
 pub mod day21;
+pub mod day22;
 pub mod day24;