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use {
anyhow::{
anyhow,
Context,
Result,
},
std::{
env::args,
fs::read_to_string,
path::Path,
},
};
fn read_input<T: AsRef<Path>>(filename: T) -> Result<String> {
read_to_string(filename).context("Could not read {filename}")
}
fn find_sequence(input: &str, len: usize) -> Option<usize> {
input.as_bytes().windows(len).enumerate().find_map(|(pos, win)| {
for i in 0..len {
if win[(i + 1)..].contains(&win[i]) {
return None
}
}
Some(pos + len)
})
}
fn part1(input: &str) -> Result<usize> {
find_sequence(input, 4).ok_or_else(|| anyhow!("No match found"))
}
fn part2(input: &str) -> Result<usize> {
find_sequence(input, 14).ok_or_else(|| anyhow!("No match found"))
}
fn main() -> Result<()> {
let ( do_part_1, do_part_2 ) = aoc::do_parts();
let filename = args().nth(1).ok_or_else(|| anyhow!("Missing input filename"))?;
let input = read_input(filename).context("Could not read input")?;
if do_part_1 {
let solution = part1(&input).context("No solution for part 1")?;
println!("Part1, solution found to be: {}", solution);
}
if do_part_2 {
let solution = part2(&input).context("No solution for part 2")?;
println!("Part2, solution found to be: {}", solution);
}
Ok(())
}
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