Day4 Rust

day4/rust/.gitignore

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+target

day4/rust/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rust"
+version = "0.1.0"

day4/rust/Cargo.toml

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+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day4/rust/src/main.rs

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+use std::collections::VecDeque;
+
+struct Card {
+    _id: usize,
+    winning_numbers: Vec<usize>,
+    scratched_numbers: Vec<usize>,
+}
+
+fn main() {
+    let stdin = std::io::stdin();
+
+    let mut cards = Vec::new();
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let (card_id_str, numbers) = line.split_once(':').unwrap();
+
+        let card_id = card_id_str
+            .split_once(' ')
+            .unwrap()
+            .1
+            .trim()
+            .parse()
+            .unwrap();
+
+        let (winning_numbers_str, scratched_numbers_str) = numbers.split_once('|').unwrap();
+
+        let winning_numbers = winning_numbers_str
+            .split(' ')
+            .filter(|e| e.len() > 0)
+            .map(|e| e.parse().unwrap())
+            .collect();
+
+        let scratched_numbers = scratched_numbers_str
+            .split(' ')
+            .filter(|e| e.len() > 0)
+            .map(|e| e.parse().unwrap())
+            .collect();
+
+        cards.push(Card {
+            _id: card_id,
+            winning_numbers,
+            scratched_numbers,
+        });
+    }
+
+    let mut part1 = 0;
+    let mut part2 = 0;
+
+    let mut foresight = VecDeque::new();
+
+    for card in &cards {
+        let mut score = 0;
+        let mut win_num = 0;
+
+        let card_num = foresight.pop_front().unwrap_or(0) + 1;
+        part2 += card_num;
+
+        for scratched_number in &card.scratched_numbers {
+            if card.winning_numbers.contains(&scratched_number) {
+                win_num += 1;
+                if score == 0 {
+                    score = 1;
+                } else {
+                    score *= 2;
+                }
+            }
+        }
+
+        for i in 0..win_num {
+            if let Some(n) = foresight.get(i) {
+                foresight[i] = n + card_num;
+            } else {
+                foresight.push_back(card_num);
+            }
+        }
+
+        part1 += score;
+    }
+
+    println!("{}", part1);
+    println!("{}", part2);
+}