days 5 + 6

day06/Cargo.lock

@@ -0,0 +1,16 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day06"
+version = "0.1.0"
+dependencies = [
+ "rustc-hash",
+]
+
+[[package]]
+name = "rustc-hash"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"

day06/Cargo.toml

@@ -0,0 +1,9 @@
+[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]
+rustc-hash = "1.1.0"

day06/src/main.rs

@@ -0,0 +1,17 @@
+use rustc_hash::FxHashSet;
+const PACKET_WINDOW_SIZE: usize = 4;
+const MESSAGE_WINDOW_SIZE: usize = 14;
+
+fn main() {
+    let s = std::fs::read_to_string("/dev/stdin").unwrap();
+    println!("P1: {}, P2: {}", find_index(&s, PACKET_WINDOW_SIZE), find_index(&s, MESSAGE_WINDOW_SIZE));
+}
+
+fn find_index(s: &str, window_size: usize) -> usize {
+    for (count, window) in s.chars().collect::<Vec<char>>().windows(window_size).enumerate(){
+        if FxHashSet::from_iter(window).len() == window_size {
+            return count + window_size;
+        }
+    }
+    0
+}