Added day 4

src/day4/mod.rs

@@ -1,12 +1,28 @@
 use std::{collections::HashSet, path::Path, str::FromStr};
 
+use itertools::Itertools;
+
 use crate::input::{AdventError, read_into_vec};
 
 impl FromStr for ScratchGame {
     type Err = AdventError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        todo!()
+        let split = s.split(':').collect_vec();
+        let id = split[0].split_whitespace().collect_tuple::<(&str, &str)>().ok_or(AdventError("Game Id not found.".into()))?.1.parse::<i32>()?;
+        let split = split[1].split('|').collect_vec();
+        let my_numbers: HashSet<i32> = split[0].trim().split_whitespace().map(|x| {
+            x.parse::<i32>()
+        }).collect::<Result<HashSet<_>, _>>()?;
+        let winning_numbers: HashSet<i32> = split[1].trim().split_whitespace().map(|x| -> Result<i32, AdventError> {
+            x.parse::<i32>().map_err(Into::into)
+        }).collect::<Result<HashSet<_>, _>>()?;
+        
+        Ok(ScratchGame {
+            id,
+            my_numbers,
+            winning_numbers
+        })
     }
 }
 
@@ -17,10 +33,33 @@ struct ScratchGame {
 }
 
 pub fn one() -> Result<u32, AdventError> {
-    let games = read_into_vec::<ScratchGame>(Path::new("resources/input4.txt"));
-    Ok(0)
+    let games = read_into_vec::<ScratchGame>(Path::new("resources/input4.txt"))?;
+    Ok(games.into_iter().fold(Ok(0), |acc: Result<u64, AdventError>, game: ScratchGame| {
+        let acc = acc?;
+        let my_winning_numbers = game.my_numbers.intersection(&game.winning_numbers);
+        Ok(acc + match my_winning_numbers.count() {
+            0 => 0,
+            x => (2 as u64).pow((x-1).try_into()?)
+        })
+    })? as u32)
 }
 
 pub fn two() -> Result<u32, AdventError> {
-    Ok(0)
+    let games = read_into_vec::<ScratchGame>(Path::new("resources/input4.txt"))?;
+    let mut vec = Vec::<u32>::new();
+    vec.resize(games.len(), 1);
+    
+    for game in games.into_iter() {
+        let my_winning_numbers = game.my_numbers.intersection(&game.winning_numbers);
+        let nr_free_tickets = my_winning_numbers.count() as i32;
+        
+        for index in game.id..(game.id + nr_free_tickets ) {
+            let nr_to_count = vec[(game.id - 1) as usize];
+            for _ in 0..nr_to_count {
+                vec[index as usize] += 1;
+            }       
+        }
+    }
+
+    Ok(vec.iter().sum())
 }

src/input/mod.rs

@@ -1,4 +1,4 @@
-use std::{io::{BufReader, BufRead, self}, fs::File, str::FromStr, path::Path, convert::Infallible, num::ParseIntError};
+use std::{io::{BufReader, BufRead, self}, fs::File, str::FromStr, path::Path, convert::Infallible, num::{ParseIntError, TryFromIntError}};
 
 #[derive(Debug)]
 pub struct AdventError(pub String);
@@ -21,6 +21,12 @@ impl From<Infallible> for AdventError {
     }
 }
 
+impl From<TryFromIntError> for AdventError {
+    fn from(e: TryFromIntError) -> Self {
+        AdventError(e.to_string())
+    }
+}
+
 pub fn read_into_vec<T:FromStr>(file_path : &Path) -> Result<Vec<T>, AdventError> where AdventError: From<<T as FromStr>::Err> {
     let file = File::open(file_path).expect("no such file");
     let buf = BufReader::new(file);