add day 4, part 1

day04/common.rs

@@ -0,0 +1,67 @@
+// 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/>.
+
+use std::io;
+use std::ops::RangeInclusive;
+
+pub struct Assignments {}
+
+#[derive(Debug)]
+pub struct Assignment {
+    range1: RangeInclusive<u8>,
+    range2: RangeInclusive<u8>,
+}
+
+impl Iterator for Assignments {
+    type Item = Result<Assignment, &'static str>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(line) = io::stdin().lines().next() {
+            let line = line.unwrap();
+            if line.len() > 0 {
+                if let Some((left, right)) = line.split_once(',') {
+                    if let (Some((s1, e1)), Some((s2, e2))) =
+                        (left.split_once('-'), right.split_once('-'))
+                    {
+                        if let (Ok(s1), Ok(e1), Ok(s2), Ok(e2)) = (
+                            s1.parse::<u8>(),
+                            e1.parse::<u8>(),
+                            s2.parse::<u8>(),
+                            e2.parse::<u8>(),
+                        ) {
+                            return Some(Ok(Assignment::new(s1..=e1, s2..=e2)));
+                        }
+                    }
+                }
+                return Some(Err("input file contains invalid line"));
+            }
+        }
+        None
+    }
+}
+
+impl Assignment {
+    pub fn new(range1: RangeInclusive<u8>, range2: RangeInclusive<u8>) -> Self {
+        Self {
+            range1: range1,
+            range2: range2,
+        }
+    }
+
+    pub fn has_obsolete_range(&self) -> bool {
+        self.range1.contains(self.range2.start()) && self.range1.contains(self.range2.end())
+            || self.range2.contains(self.range1.start()) && self.range2.contains(self.range1.end())
+    }
+}

day04/part1.rs

@@ -0,0 +1,32 @@
+// 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: ./part1 < input
+
+pub mod common;
+
+use common::Assignments;
+
+fn main() -> Result<(), &'static str> {
+    let assignments = Assignments {};
+    let mut result = 0;
+    for assignment in assignments {
+        if assignment?.has_obsolete_range() {
+            result += 1;
+        }
+    }
+    println!("{result}");
+    Ok(())
+}

day04/testinput

@@ -0,0 +1,7 @@
+2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8
+