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|
use anyhow::Result;
use std::env::args;
use std::fs::File;
use std::io::{BufRead, BufReader};
use std::path::Path;
const SUM: usize = 2020;
fn read_input<T: AsRef<Path>>(filename: T) -> Result<Vec<usize>> {
let f = File::open(filename)?;
let reader = BufReader::new(f);
let values = reader.lines()
.map(|v| v.unwrap().parse::<usize>().unwrap()).collect();
Ok(values)
}
fn part1(input: &[usize]) -> Option<usize> {
for first in input {
for second in input {
if first + second == SUM {
return Some(first * second);
}
}
}
None
}
fn part2(input: &[usize]) -> Option<usize> {
for first in input {
for second in input {
for third in input {
if first + second + third == SUM {
return Some(first * second * third);
}
}
}
}
None
}
fn main() {
let ( do_part_1, do_part_2 ) = aoc::do_parts();
let filename = match args().nth(1) {
Some(f) => f,
None => {
eprintln!("Missing input filename");
std::process::exit(1);
},
};
match read_input(filename) {
Ok(input) => {
if do_part_1 {
match part1(&input) {
Some(solution) => println!("Part1, product found to be: {}", solution),
None => {
eprintln!("Part1, no solution found");
std::process::exit(1);
}
};
}
if do_part_2 {
match part2(&input) {
Some(solution) => println!("Part2, product found to be: {}", solution),
None => {
eprintln!("Part2, no solution found");
std::process::exit(1);
}
};
}
},
Err(err) => eprintln!("Could not read input: {}", err),
}
}
|
