add day 6, part 2

day06/part2.rs

@@ -0,0 +1,36 @@
+// Copyright 2022 Christian Ulrich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// usage: ./part2 < input
+
+pub mod common;
+
+use common::DatastreamWindows;
+
+fn main() -> Result<(), &'static str> {
+    const WINDOW_SIZE: usize = 14;
+    let mut result = WINDOW_SIZE;
+    for window in DatastreamWindows::<WINDOW_SIZE>::from_stdin()? {
+        if window
+            .iter()
+            .all(|byte| window.iter().filter(|b| b == &byte).count() == 1)
+        {
+            break;
+        }
+        result += 1;
+    }
+    println!("{result}");
+    Ok(())
+}