Solution for day 22

day22/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "day22"
+version = "0.1.0"
+authors = ["inga-lovinde <52715130+inga-lovinde@users.noreply.github.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day22/src/main.rs

@@ -0,0 +1,128 @@
+use std::collections::{HashSet, HashMap, VecDeque};
+use std::error::Error;
+use std::io::{self, BufRead};
+
+#[derive(Debug)]
+struct GameResult {
+    winner: usize,
+    cards: [VecDeque<usize>; 2],
+}
+
+fn game_easy(mut cards: [VecDeque<usize>; 2]) -> GameResult {
+    loop {
+        let card0 = cards[0].pop_front().unwrap();
+        let card1 = cards[1].pop_front().unwrap();
+
+        if card0 < card1 {
+            cards[1].push_back(card1);
+            cards[1].push_back(card0);
+        } else if card0 > card1 {
+            cards[0].push_back(card0);
+            cards[0].push_back(card1);
+        } else {
+            panic!("cards are equal");
+        }
+
+        if cards[0].len() == 0 {
+            return GameResult {
+                winner: 1,
+                cards,
+            }
+        }
+
+        if cards[1].len() == 0 {
+            return GameResult {
+                winner: 0,
+                cards,
+            }
+        }
+    }
+}
+
+fn game_hard(original_cards: &[VecDeque<usize>; 2]) -> GameResult {
+    let mut cards = original_cards.clone();
+    let mut states = HashSet::new();
+
+    loop {
+        if states.contains(&cards[0]) {
+            //println!("loop return from game {}", current_game_count);
+            //result_cache.insert(original_cards.clone(), 0);
+            return GameResult {
+                winner: 0,
+                cards,
+            };
+        }
+
+        states.insert(cards[0].clone());
+
+        let card0 = cards[0].pop_front().unwrap();
+        let card1 = cards[1].pop_front().unwrap();
+
+        let round_winner = if cards[0].len() >= card0 && cards[1].len() >= card1 {
+            game_hard(&[cards[0].iter().cloned().take(card0).collect(), cards[1].iter().cloned().take(card1).collect()]).winner
+        } else if card0 < card1 {
+            1
+        } else if card0 > card1 {
+            0
+        } else {
+            panic!("cards are equal");
+        };
+
+        match round_winner {
+            0 => {
+                cards[0].push_back(card0);
+                cards[0].push_back(card1);
+            },
+            1 => {
+                cards[1].push_back(card1);
+                cards[1].push_back(card0);
+            },
+            _ => panic!("wrong winner value"),
+        }
+
+        if cards[0].len() == 0 {
+            //println!("winner 1 return from game {}", current_game_count);
+            return GameResult {
+                winner: 1,
+                cards,
+            };
+        }
+
+        if cards[1].len() == 0 {
+            //println!("winner 0 return from game {}", current_game_count);
+            return GameResult {
+                winner: 0,
+                cards,
+            };
+        }
+    }
+}
+
+fn handle_result(game_result: GameResult) {
+    let mut sum = 0;
+    let len = game_result.cards[game_result.winner].len();
+    for i in 0..len {
+        sum += (len-i) * game_result.cards[game_result.winner][i];
+    }
+    println!("{:?}", game_result);
+    println!("{}", sum);
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let stdin = io::stdin();
+    let mut cards: [VecDeque<usize>; 2] = Default::default();
+    let mut current_player = usize::MAX;
+    for line_result in stdin.lock().lines() {
+        let line = line_result?;
+        if line.starts_with("Player") {
+            current_player = line.strip_prefix("Player ").unwrap().strip_suffix(":").unwrap().parse::<usize>()? - 1;
+        } else if line != "" {
+            cards[current_player].push_back(line.parse()?);
+        }
+    }
+
+    handle_result(game_easy(cards.clone()));
+    handle_result(game_hard(&cards));
+
+    Ok(())
+}