add day 2

day02/part1.rs

@@ -0,0 +1,106 @@
+// 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
+
+use std::convert::TryFrom;
+use std::io;
+
+#[derive(Debug, Clone, Copy)]
+enum Item {
+    Rock = 1,
+    Paper = 2,
+    Scissors = 3,
+}
+
+enum Outcome {
+    Lose = 0,
+    Draw = 3,
+    Win = 6,
+}
+
+struct Round {
+    me: Item,
+    other: Item,
+}
+
+struct Rounds {}
+
+impl TryFrom<&str> for Item {
+    type Error = &'static str;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "A" | "X" => Ok(Item::Rock),
+            "B" | "Y" => Ok(Item::Paper),
+            "C" | "Z" => Ok(Item::Scissors),
+            _ => Err("invalid value"),
+        }
+    }
+}
+
+impl Round {
+    pub fn new(me: Item, other: Item) -> Self {
+        Self {
+            me: me,
+            other: other,
+        }
+    }
+
+    fn outcome(&self) -> Outcome {
+        match (self.me, self.other) {
+            (Item::Rock, Item::Paper) => Outcome::Lose,
+            (Item::Rock, Item::Scissors) => Outcome::Win,
+            (Item::Paper, Item::Rock) => Outcome::Win,
+            (Item::Paper, Item::Scissors) => Outcome::Lose,
+            (Item::Scissors, Item::Rock) => Outcome::Lose,
+            (Item::Scissors, Item::Paper) => Outcome::Win,
+            _ => Outcome::Draw,
+        }
+    }
+
+    pub fn score(&self) -> usize {
+        self.outcome() as usize + self.me as usize
+    }
+}
+
+impl Iterator for Rounds {
+    type Item = Result<Round, &'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 (Ok(other), Ok(me)) = (Item::try_from(left), Item::try_from(right)) {
+                        return Some(Ok(Round::new(me, other)));
+                    }
+                }
+                return Some(Err("input file contains invalid line"));
+            }
+        }
+        None
+    }
+}
+
+fn main() -> Result<(), &'static str> {
+    let rounds = Rounds {};
+    let mut result = 0;
+    for round in rounds {
+        result += round?.score();
+    }
+    println!("{result}");
+    Ok(())
+}

day02/part2.rs

@@ -0,0 +1,134 @@
+// 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
+
+use std::convert::TryFrom;
+use std::io;
+
+#[derive(Debug, Clone, Copy)]
+enum Item {
+    Rock = 1,
+    Paper = 2,
+    Scissors = 3,
+}
+
+enum Outcome {
+    Lose = 0,
+    Draw = 3,
+    Win = 6,
+}
+
+struct Round {
+    me: Item,
+    other: Item,
+}
+
+struct Rounds {}
+
+impl TryFrom<&str> for Item {
+    type Error = &'static str;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "A" => Ok(Item::Rock),
+            "B" => Ok(Item::Paper),
+            "C" => Ok(Item::Scissors),
+            _ => Err("invalid value"),
+        }
+    }
+}
+
+impl TryFrom<&str> for Outcome {
+    type Error = &'static str;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "X" => Ok(Outcome::Lose),
+            "Y" => Ok(Outcome::Draw),
+            "Z" => Ok(Outcome::Win),
+            _ => Err("invalid value"),
+        }
+    }
+}
+
+impl Round {
+    pub fn new(me: Item, other: Item) -> Self {
+        Self {
+            me: me,
+            other: other,
+        }
+    }
+
+    pub fn with_outcome(other: Item, outcome: Outcome) -> Self {
+        let me = match (other, outcome) {
+            (Item::Rock, Outcome::Lose) => Item::Scissors,
+            (Item::Rock, Outcome::Win) => Item::Paper,
+            (Item::Paper, Outcome::Lose) => Item::Rock,
+            (Item::Paper, Outcome::Win) => Item::Scissors,
+            (Item::Scissors, Outcome::Lose) => Item::Paper,
+            (Item::Scissors, Outcome::Win) => Item::Rock,
+            _ => other,
+        };
+        Self::new(me, other)
+    }
+
+    fn outcome(&self) -> Outcome {
+        match (self.me, self.other) {
+            (Item::Rock, Item::Paper) => Outcome::Lose,
+            (Item::Rock, Item::Scissors) => Outcome::Win,
+            (Item::Paper, Item::Rock) => Outcome::Win,
+            (Item::Paper, Item::Scissors) => Outcome::Lose,
+            (Item::Scissors, Item::Rock) => Outcome::Lose,
+            (Item::Scissors, Item::Paper) => Outcome::Win,
+            _ => Outcome::Draw,
+        }
+    }
+
+    pub fn score(&self) -> usize {
+        self.outcome() as usize + self.me as usize
+    }
+}
+
+impl Iterator for Rounds {
+    type Item = Result<Round, &'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 (Ok(item), Ok(outcome)) =
+                        (Item::try_from(left), Outcome::try_from(right))
+                    {
+                        return Some(Ok(Round::with_outcome(item, outcome)));
+                    }
+                }
+                return Some(Err("input file contains invalid line"));
+            }
+        }
+        None
+    }
+}
+
+fn main() -> Result<(), &'static str> {
+    let rounds = Rounds {};
+    let mut result = 0;
+    for round in rounds {
+        result += round?.score();
+    }
+    println!("{result}");
+    Ok(())
+}

day02/testinput

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z