Day 4

src/day4/mod.rs

@@ -0,0 +1,106 @@
+use std::collections::HashMap;
+
+use crate::utils::Day;
+
+#[derive(Debug)]
+pub struct Day4 {
+    pub input: String,
+    pub acc: usize,
+    pub cards: HashMap::<usize /* Card # */, Vec<usize> /* (won card indexes) */>
+}
+
+impl Day4 {
+    fn recurse(&mut self, cards: &Vec<usize>) {
+        for card in cards {
+            self.acc += 1;
+            
+            if let Some(won_cards) = self.cards.get(card) {
+                self.recurse(&won_cards.clone())
+            }
+        }
+    }
+}
+
+impl Day for Day4 {
+    fn part1(&mut self) -> String {
+        let mut sum = 0usize;
+        
+        for line in self.input.lines() {
+            let (winning, numbers) = line.split_once(": ").unwrap().1.split_once(" | ").unwrap();
+            let winning = winning.split_whitespace().collect::<Vec<_>>();
+
+            let mut winning_numbers = Vec::<&str>::new();
+            for number in numbers.split_whitespace() {
+                if winning.contains(&number) && !winning_numbers.contains(&number) {
+                    winning_numbers.push(number);
+                }
+            }
+
+            if winning_numbers.len() != 0 {
+                sum += winning_numbers.iter().skip(1).fold(1usize, |acc, _| acc * 2);
+            }
+        }
+
+        sum.to_string()
+    }
+
+    fn part2(&mut self) -> String {
+        self.cards = HashMap::<usize /* Card # */, Vec<usize> /* won card indexes */>::new();
+        for (i, line) in self.input.lines().enumerate() {
+            let (winning, numbers) = line.split_once(": ").unwrap().1.split_once(" | ").unwrap();
+            let winning = winning.split_whitespace().collect::<Vec<_>>();
+
+            let mut winning_numbers = Vec::<&str>::new();
+            for number in numbers.split_whitespace() {
+                if winning.contains(&number) && !winning_numbers.contains(&number) {
+                    winning_numbers.push(number);
+                }
+            }
+
+            self.cards.insert(i + 1, winning_numbers.into_iter().enumerate().map(|(j, _)| (i + 1) + (j + 1)).collect());
+        }
+
+        self.recurse(&self.cards.keys().map(|e| *e).collect::<Vec<_>>());
+
+        self.acc.to_string()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use crate::{day4::Day4, utils::Day};
+
+    #[test]
+    fn passes_example_1() {
+        dbg!(Day4 {
+            input: r#"Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11"#
+                .to_string(),
+            acc: 0usize,
+            cards: HashMap::new()
+        }
+        .solve(1));
+    }
+
+    #[test]
+    fn passes_example_2() {
+        dbg!(Day4 {
+            input: r#"Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11"#
+                .to_string(),
+                acc: 0usize,
+                cards: HashMap::new()
+        }
+        .solve(2));
+    }
+}

src/main.rs

@@ -1,15 +1,16 @@
 use std::{
     io::Write,
-    time::{Duration, Instant},
+    time::{Duration, Instant}, collections::HashMap,
 };
 
 use clap::{Parser, Subcommand};
 
-use crate::{day1::Day1, day2::Day2, day3::Day3, utils::Day};
+use crate::{day1::Day1, day2::Day2, day3::Day3, utils::Day, day4::Day4};
 
 pub mod day1;
 pub mod day2;
 pub mod day3;
+pub mod day4;
 pub mod utils;
 
 #[derive(Parser)]
@@ -76,13 +77,25 @@ async fn main() {
                     games: vec![],
                 }),
                 3 => Box::new(Day3 { input: response }),
+                4 => Box::new(Day4 { input: response, acc: 0usize, cards: HashMap::new() }),
                 _ => panic!("Invalid day #"),
             };
             let start = std::time::Instant::now();
             let result = day.solve(part);
             let end = std::time::Instant::now();
             println!("Solution: {result}");
-            println!("Solved in {}ns", (end - start).as_nanos() as f64 / 1000.0);
+
+            let timing = (end - start).as_nanos();
+            let (timing, timing_units) = if timing >= 1000000000 {
+                (timing as f64 / 1000000000.0, "s")
+            } else if timing >= 1000000 {
+                (timing as f64 / 1000000.0, "ms")
+            } else if timing >= 1000 {
+                (timing as f64 / 1000.0, "µs")
+            } else {
+                (timing as f64, "ns")
+            };
+            println!("Solved in {timing}{timing_units}");
         }
         Subcommands::Benchmark {
             day,
@@ -109,6 +122,7 @@ async fn main() {
                     games: vec![],
                 }),
                 3 => Box::new(Day3 { input: response }),
+                4 => Box::new(Day4 { input: response, acc: 0usize, cards: HashMap::new() }),
                 _ => panic!("Invalid day #"),
             };
             let mut timings = Vec::<Duration>::new();