From 035f8e86ac2dff49f0dd252c3babce04b86ca183 Mon Sep 17 00:00:00 2001
From: MasterofJOKers <joker@someserver.de>
Date: Mon, 19 Dec 2022 14:34:02 +0100
Subject: [PATCH] day06: Add part 1

Borrow-checker hindered me to keep the same HashSet around all the time
and just clear it, so it feels a little inefficient to have a new set
every time.
---
 day06/Cargo.lock  |  7 +++++++
 day06/Cargo.toml  |  8 ++++++++
 day06/src/main.rs | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 day06/Cargo.lock
 create mode 100644 day06/Cargo.toml
 create mode 100644 day06/src/main.rs

diff --git a/day06/Cargo.lock b/day06/Cargo.lock
new file mode 100644
index 0000000..0c65426
--- /dev/null
+++ b/day06/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day06"
+version = "0.1.0"
diff --git a/day06/Cargo.toml b/day06/Cargo.toml
new file mode 100644
index 0000000..2f276f3
--- /dev/null
+++ b/day06/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day06"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day06/src/main.rs b/day06/src/main.rs
new file mode 100644
index 0000000..623064d
--- /dev/null
+++ b/day06/src/main.rs
@@ -0,0 +1,37 @@
+use std::collections::HashSet;
+use std::error;
+use std::fs::File;
+use std::io::prelude::*;
+
+fn main() -> Result<(), Box<dyn error::Error>> {
+	let mut f = File::open("input.txt")?;
+
+	let mut buf = [0; 32];
+	let mut pos = 0;
+	let mut found = false;
+	let mut n = f.read(&mut buf[3..])?;
+	while n > 0 {
+		for i in 4..(4 + n) {
+			pos += 1;
+			// println!("{}", std::str::from_utf8(&buf[(i - 4)..i]).unwrap());
+			// skip if we read uninitialized data from first run
+			if buf[i - 4] == 0 {
+				continue;
+			}
+			let set: HashSet<&u8> = HashSet::from_iter(&buf[(i - 4)..i]);
+			if set.len() == 4 {
+				found = true;
+				break;
+			}
+		}
+		if found {
+			break;
+		}
+		for i in 0..3 {
+			buf[i] = buf[29 + i];
+		}
+		n = f.read(&mut buf[3..])?;
+	}
+    println!("Found 4 different chars at position {}", pos);
+    Ok(())
+}