135 lines
3.6 KiB
Rust
135 lines
3.6 KiB
Rust
// Copyright 2022 Christian Ulrich
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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// usage: ./part2 < input
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use std::convert::TryFrom;
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use std::io;
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#[derive(Debug, Clone, Copy)]
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enum Item {
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Rock = 1,
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Paper = 2,
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Scissors = 3,
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}
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enum Outcome {
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Lose = 0,
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Draw = 3,
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Win = 6,
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}
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struct Round {
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me: Item,
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other: Item,
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}
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struct Rounds {}
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impl TryFrom<&str> for Item {
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type Error = &'static str;
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fn try_from(value: &str) -> Result<Self, Self::Error> {
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match value {
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"A" => Ok(Item::Rock),
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"B" => Ok(Item::Paper),
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"C" => Ok(Item::Scissors),
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_ => Err("invalid value"),
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}
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}
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}
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impl TryFrom<&str> for Outcome {
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type Error = &'static str;
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fn try_from(value: &str) -> Result<Self, Self::Error> {
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match value {
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"X" => Ok(Outcome::Lose),
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"Y" => Ok(Outcome::Draw),
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"Z" => Ok(Outcome::Win),
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_ => Err("invalid value"),
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}
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}
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}
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impl Round {
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pub fn new(me: Item, other: Item) -> Self {
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Self {
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me: me,
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other: other,
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}
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}
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pub fn with_outcome(other: Item, outcome: Outcome) -> Self {
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let me = match (other, outcome) {
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(Item::Rock, Outcome::Lose) => Item::Scissors,
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(Item::Rock, Outcome::Win) => Item::Paper,
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(Item::Paper, Outcome::Lose) => Item::Rock,
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(Item::Paper, Outcome::Win) => Item::Scissors,
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(Item::Scissors, Outcome::Lose) => Item::Paper,
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(Item::Scissors, Outcome::Win) => Item::Rock,
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_ => other,
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};
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Self::new(me, other)
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}
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fn outcome(&self) -> Outcome {
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match (self.me, self.other) {
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(Item::Rock, Item::Paper) => Outcome::Lose,
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(Item::Rock, Item::Scissors) => Outcome::Win,
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(Item::Paper, Item::Rock) => Outcome::Win,
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(Item::Paper, Item::Scissors) => Outcome::Lose,
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(Item::Scissors, Item::Rock) => Outcome::Lose,
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(Item::Scissors, Item::Paper) => Outcome::Win,
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_ => Outcome::Draw,
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}
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}
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pub fn score(&self) -> usize {
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self.outcome() as usize + self.me as usize
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}
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}
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impl Iterator for Rounds {
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type Item = Result<Round, &'static str>;
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fn next(&mut self) -> Option<Self::Item> {
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if let Some(line) = io::stdin().lines().next() {
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let line = line.unwrap();
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if line.len() > 0 {
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if let Some((left, right)) = line.split_once(' ') {
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if let (Ok(item), Ok(outcome)) =
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(Item::try_from(left), Outcome::try_from(right))
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{
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return Some(Ok(Round::with_outcome(item, outcome)));
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}
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}
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return Some(Err("input file contains invalid line"));
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}
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}
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None
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}
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}
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fn main() -> Result<(), &'static str> {
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let rounds = Rounds {};
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let mut result = 0;
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for round in rounds {
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result += round?.score();
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}
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println!("{result}");
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Ok(())
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}
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