From d49d6dabc7c66263ae630de07a5ccf23a5c66c76 Mon Sep 17 00:00:00 2001
From: Gard Spreemann <gspr@nonempty.org>
Date: Wed, 8 Dec 2021 12:27:27 +0100
Subject: Day 6

---
 06/Cargo.toml    | 15 +++++++++++++++
 06/input.txt     |  1 +
 06/src/part-1.rs | 40 ++++++++++++++++++++++++++++++++++++++++
 06/src/part-2.rs | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 06/test.txt      |  2 ++
 5 files changed, 107 insertions(+)
 create mode 100644 06/Cargo.toml
 create mode 100644 06/input.txt
 create mode 100644 06/src/part-1.rs
 create mode 100644 06/src/part-2.rs
 create mode 100644 06/test.txt

diff --git a/06/Cargo.toml b/06/Cargo.toml
new file mode 100644
index 0000000..29ca8d8
--- /dev/null
+++ b/06/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "day-06"
+version = "0.1.0"
+authors = ["Gard Spreemann <gspr@nonempty.org>"]
+edition = "2021"
+
+[[bin]]
+name = "part-1"
+path = "src/part-1.rs"
+
+[[bin]]
+name = "part-2"
+path = "src/part-2.rs"
+
+[dependencies]
diff --git a/06/input.txt b/06/input.txt
new file mode 100644
index 0000000..3e35679
--- /dev/null
+++ b/06/input.txt
@@ -0,0 +1 @@
+4,1,1,4,1,2,1,4,1,3,4,4,1,5,5,1,3,1,1,1,4,4,3,1,5,3,1,2,5,1,1,5,1,1,4,1,1,1,1,2,1,5,3,4,4,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,5,1,1,1,4,1,2,3,5,1,2,2,4,1,4,4,4,1,2,5,1,2,1,1,1,1,1,1,4,1,1,4,3,4,2,1,3,1,1,1,3,5,5,4,3,4,1,5,1,1,1,2,2,1,3,1,2,4,1,1,3,3,1,3,3,1,1,3,1,5,1,1,3,1,1,1,5,4,1,1,1,1,4,1,1,3,5,4,3,1,1,5,4,1,1,2,5,4,2,1,4,1,1,1,1,3,1,1,1,1,4,1,1,1,1,2,4,1,1,1,1,3,1,1,5,1,1,1,1,1,1,4,2,1,3,1,1,1,2,4,2,3,1,4,1,2,1,4,2,1,4,4,1,5,1,1,4,4,1,2,2,1,1,1,1,1,1,1,1,1,1,1,4,5,4,1,3,1,3,1,1,1,5,3,5,5,2,2,1,4,1,4,2,1,4,1,2,1,1,2,1,1,5,4,2,1,1,1,2,4,1,1,1,1,2,1,1,5,1,1,2,2,5,1,1,1,1,1,2,4,2,3,1,2,1,5,4,5,1,4
diff --git a/06/src/part-1.rs b/06/src/part-1.rs
new file mode 100644
index 0000000..5a1660e
--- /dev/null
+++ b/06/src/part-1.rs
@@ -0,0 +1,40 @@
+use std::io::{BufRead};
+
+pub fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() != 2 { panic!("Need exactly 1 argument"); }
+    let num_days: usize = args[1].parse().expect("Need number of days as argument");
+    
+    let mut stdin = std::io::stdin();
+    let mut handle = stdin.lock();
+
+    let input: String = {
+        let mut buf = String::new();
+        handle.read_line(&mut buf).unwrap();
+        String::from(buf.trim_end())
+    };
+
+    let mut fishes: Vec<u64> = input.split(',').map(|w| w.parse().expect("Malformed input")).collect();
+
+    for i in 0..num_days {
+        let mut new_fish_count: usize = 0;
+        for fish in (&mut fishes).into_iter() {
+            if *fish == 0 {
+                new_fish_count += 1;
+                *fish = 6;
+            }
+            else { *fish -= 1; }
+        }
+        fishes.extend(std::iter::repeat(8).take(new_fish_count));
+
+        /*
+        print!("After day {:>width$}: ", i, width = format!("{}", num_days).len());
+        for fish in (& fishes).into_iter() {
+            print!("{} ", *fish);
+        }
+        println!("");
+        */
+    }
+
+    println!("After {} days there are {} fishies", num_days, fishes.len());
+}
diff --git a/06/src/part-2.rs b/06/src/part-2.rs
new file mode 100644
index 0000000..37d095e
--- /dev/null
+++ b/06/src/part-2.rs
@@ -0,0 +1,49 @@
+use std::io::{BufRead};
+
+#[derive(Clone, Copy)]
+struct FishSchool {
+    state: u64,
+    size: usize
+}
+
+pub fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() != 2 { panic!("Need exactly 1 argument"); }
+    let num_days: usize = args[1].parse().expect("Need number of days as argument");
+    
+    let mut stdin = std::io::stdin();
+    let mut handle = stdin.lock();
+
+    let input: String = {
+        let mut buf = String::new();
+        handle.read_line(&mut buf).unwrap();
+        String::from(buf.trim_end())
+    };
+
+    let mut schools: Vec<FishSchool> = input.split(',').map(|w| FishSchool {
+        state: w.parse().expect("Malformed input"),
+        size: 1} ).collect();
+
+    for i in 0..num_days {
+        let mut new_fish_count: usize = 0;
+        for school in (&mut schools).into_iter() {
+            if school.state == 0 {
+                new_fish_count += school.size;
+                school.state = 6;
+            }
+            else { school.state -= 1; }
+        }
+        schools.push(FishSchool { state: 8, size: new_fish_count });
+
+        /*
+        print!("After day {:>width$}: ", i, width = format!("{}", num_days).len());
+        for school in (& schools).into_iter() {
+            for _ in 0..school.size { print!("{} ", school.state); }
+        }
+        println!("");
+        */
+    }
+
+    let n: usize = schools.into_iter().map(|school| school.size).sum();
+    println!("After {} days there are {} fishies", num_days, n);
+}
diff --git a/06/test.txt b/06/test.txt
new file mode 100644
index 0000000..9792d05
--- /dev/null
+++ b/06/test.txt
@@ -0,0 +1,2 @@
+3,4,3,1,2
+
-- 
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