From 4b4d4bdadda5dfd5528d02bc8666738ff633291f Mon Sep 17 00:00:00 2001
From: Lars Martens <lars@martens.red>
Date: Mon, 6 Dec 2021 12:38:41 +0100
Subject: [PATCH] Day 6

---
 input/06-test.txt |  1 +
 input/06.txt      |  1 +
 src/bin/06.rs     | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)
 create mode 100644 input/06-test.txt
 create mode 100644 input/06.txt
 create mode 100644 src/bin/06.rs

diff --git a/input/06-test.txt b/input/06-test.txt
new file mode 100644
index 0000000..a7af2b1
--- /dev/null
+++ b/input/06-test.txt
@@ -0,0 +1 @@
+3,4,3,1,2
\ No newline at end of file
diff --git a/input/06.txt b/input/06.txt
new file mode 100644
index 0000000..877bf65
--- /dev/null
+++ b/input/06.txt
@@ -0,0 +1 @@
+1,1,3,5,1,1,1,4,1,5,1,1,1,1,1,1,1,3,1,1,1,1,2,5,1,1,1,1,1,2,1,4,1,4,1,1,1,1,1,3,1,1,5,1,1,1,4,1,1,1,4,1,1,3,5,1,1,1,1,4,1,5,4,1,1,2,3,2,1,1,1,1,1,1,1,1,1,1,1,1,1,5,1,1,1,1,1,1,1,1,2,2,1,1,1,1,1,5,1,1,1,3,4,1,1,1,1,3,1,1,1,1,1,4,1,1,3,1,1,3,1,1,1,1,1,3,1,5,2,3,1,2,3,1,1,2,1,2,4,5,1,5,1,4,1,1,1,1,2,1,5,1,1,1,1,1,5,1,1,3,1,1,1,1,1,1,4,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,2,1,1,1,1,2,2,1,2,1,1,1,5,5,1,1,1,1,1,1,1,1,1,1,1,1,2,2,1,1,4,2,1,4,1,1,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,1,5,1,1,1,1,1,1,1,1,3,1,1,3,3,1,1,1,3,5,1,1,4,1,1,1,1,1,4,1,1,3,1,1,1,1,1,1,1,1,2,1,5,1,1,1,1,1,1,1,1,1,1,4,1,1,1,1
\ No newline at end of file
diff --git a/src/bin/06.rs b/src/bin/06.rs
new file mode 100644
index 0000000..2c11bb6
--- /dev/null
+++ b/src/bin/06.rs
@@ -0,0 +1,38 @@
+use std::collections::VecDeque;
+
+type School = VecDeque<u64>;
+
+fn main() {
+    let mut fish = input();
+    for _ in 0..80 {
+        step(&mut fish);
+    }
+    println!("First solution: {}", sum(&fish));
+
+    let mut fish = input();
+    for _ in 0..256 {
+        step(&mut fish);
+    }
+    println!("Second solution: {}", sum(&fish));
+}
+
+fn step(fish: &mut School) {
+    let front = fish.pop_front().unwrap();
+    fish.push_back(front);
+    fish[6] += front;
+}
+
+fn sum(fish: &School) -> u64 {
+    fish.iter().sum()
+}
+
+fn input() -> School {
+    let init: School = vec![0; 9].into();
+    include_str!("../../input/06.txt")
+        .split(',')
+        .map(|n| n.parse().unwrap())
+        .fold(init, |mut acc, n| {
+            acc[n] += 1;
+            acc
+        })
+}