adventofcode2022/day01/part1.rs

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2022-12-01 20:00:15 +01:00
// 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::io;
fn accumulated_calories() -> Result<Vec<usize>, &'static str> {
let mut result = vec![];
let mut acc = None;
for line in io::stdin().lines() {
let line = line.unwrap();
if line.len() == 0 {
if let Some(value) = acc {
result.push(value);
acc = None;
}
} else {
match line.parse::<usize>() {
Ok(value) => acc = Some(acc.unwrap_or(0) + value),
Err(_) => return Err("input file contains invalid line"),
}
}
}
if let Some(value) = acc {
result.push(value)
}
Ok(result)
}
fn main() -> Result<(), &'static str> {
let mut calories = accumulated_calories()?;
calories.sort();
println!("{}", calories.last().ok_or("input file is empty")?);
Ok(())
}