From d7d1a1d840dc0a71a644110078b9fd2e3787d7a6 Mon Sep 17 00:00:00 2001
From: Julius de Jeu <julius@voidcorp.nl>
Date: Mon, 6 Dec 2021 09:12:49 +0100
Subject: [PATCH] Add Day 6

---
 input/day06  |  1 +
 src/day05.rs |  2 +-
 src/day06.rs | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs  |  5 +++-
 4 files changed, 88 insertions(+), 2 deletions(-)
 create mode 100644 input/day06
 create mode 100644 src/day06.rs

diff --git a/input/day06 b/input/day06
new file mode 100644
index 0000000..46b468a
--- /dev/null
+++ b/input/day06
@@ -0,0 +1 @@
+3,3,5,1,1,3,4,2,3,4,3,1,1,3,3,1,5,4,4,1,4,1,1,1,3,3,2,3,3,4,2,5,1,4,1,2,2,4,2,5,1,2,2,1,1,1,1,4,5,4,3,1,4,4,4,5,1,1,4,3,4,2,1,1,1,1,5,2,1,4,2,4,2,5,5,5,3,3,5,4,5,1,1,5,5,5,2,1,3,1,1,2,2,2,2,1,1,2,1,5,1,2,1,2,5,5,2,1,1,4,2,1,4,2,1,1,1,4,2,5,1,5,1,1,3,1,4,3,1,3,2,1,3,1,4,1,2,1,5,1,2,1,4,4,1,3,1,1,1,1,1,5,2,1,5,5,5,3,3,1,2,4,3,2,2,2,2,2,4,3,4,4,4,1,2,2,3,1,1,4,1,1,1,2,1,4,2,1,2,1,1,2,1,5,1,1,3,1,4,3,2,1,1,1,5,4,1,2,5,2,2,1,1,1,1,2,3,3,2,5,1,2,1,2,3,4,3,2,1,1,2,4,3,3,1,1,2,5,1,3,3,4,2,3,1,2,1,4,3,2,2,1,1,2,1,4,2,4,1,4,1,4,4,1,4,4,5,4,1,1,1,3,1,1,1,4,3,5,1,1,1,3,4,1,1,4,3,1,4,1,1,5,1,2,2,5,5,2,1,5
\ No newline at end of file
diff --git a/src/day05.rs b/src/day05.rs
index ec7033b..d915df9 100644
--- a/src/day05.rs
+++ b/src/day05.rs
@@ -37,7 +37,7 @@ impl Day for Day05 {
     }
 }
 
-fn covered_twice(vents: &Vec<Path>) -> usize {
+fn covered_twice(vents: &[Path]) -> usize {
     let mut m = HashMap::new();
     for vent in vents {
         for cover in &vent.covers {
diff --git a/src/day06.rs b/src/day06.rs
new file mode 100644
index 0000000..8cbeac4
--- /dev/null
+++ b/src/day06.rs
@@ -0,0 +1,82 @@
+use std::collections::HashMap;
+use crate::Day;
+
+pub struct Day06(Vec<u8>);
+
+impl Day for Day06 {
+    fn init(content: String) -> Self {
+        Self(content.split(',').map(|x| x.parse().expect("This is not an int!")).collect::<Vec<_>>())
+    }
+
+    fn part1(&self) -> String {
+        format!("{}", self.do_hashmap_magic(80))
+    }
+
+    fn part2(&self) -> String {
+        format!("{}", self.do_hashmap_magic(256))
+    }
+}
+
+impl Day06 {
+    fn do_hashmap_magic(&self, days: u64) -> u64 {
+        let x = self.0.clone();
+        let mut hm = HashMap::<u8, u64>::new();
+        for z in x {
+            let e = hm.entry(z).or_insert(0);
+            *e += 1;
+        }
+        for _ in 0..days {
+            let mut to_add = 0;
+            for num in 0..=8 {
+                if num == 0 {
+                    to_add = *hm.get(&0).unwrap_or(&0);
+                } else {
+                    let entry = { *hm.get(&num).unwrap_or(&0) };
+                    let prev = hm.entry(num - 1).or_insert(0);
+                    *prev = entry;
+                }
+            }
+            {
+                let en = hm.entry(8).or_insert(0);
+                *en = to_add;
+            }
+            {
+                let en = hm.entry(6).or_insert(0);
+                *en += to_add;
+            }
+        }
+        hm.values().sum::<u64>()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::day06::Day06;
+    use crate::day::Day;
+
+    const INPUT: &str = r"3,4,3,1,2";
+
+    #[test]
+    fn part1_test() {
+        let d = Day06::init(INPUT.to_string());
+        assert_eq!("5934", d.part1());
+    }
+
+    #[test]
+    fn part2_test() {
+        let d = Day06::init(INPUT.to_string());
+        assert_eq!("26984457539", d.part2());
+    }
+
+    #[test]
+    fn part1_real() {
+        let d = Day06::init(crate::load_input("06"));
+        assert_eq!("362740", d.part1());
+    }
+
+    #[test]
+    fn part2_real() {
+        let d = Day06::init(crate::load_input("06"));
+        assert_eq!("1644874076764", d.part2());
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 5258c4f..1f08bc9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,6 +6,7 @@ use crate::day02::Day02;
 use crate::day03::Day03;
 use crate::day04::Day04;
 use crate::day05::Day05;
+use crate::day06::Day06;
 use crate::day::Day;
 
 mod day;
@@ -14,6 +15,7 @@ mod day02;
 mod day03;
 mod day04;
 mod day05;
+mod day06;
 
 fn load_input(day: &str) -> String {
     read_to_string(format!("./input/day{}", day)).expect("Could not load input")
@@ -52,7 +54,8 @@ fn main() {
                                        Box::new(Day02::init(load_input("02"))),
                                        Box::new(Day03::init(load_input("03"))),
                                        Box::new(Day04::init(load_input("04"))),
-                                       Box::new(Day05::init(load_input("05")))];
+                                       Box::new(Day05::init(load_input("05"))),
+                                       Box::new(Day06::init(load_input("06")))];
 
     let _verbosity = matches.occurrences_of("v");
     if matches.is_present("all") {