AoC2022/src/bin/day6.rs

use std::error::Error;
use std::fs::File;
use std::io::{self, BufRead};

fn find_sequence(line: &str, len: usize) -> usize {
    let mut answer = 0;

    for i in 0..line.len() - len {
        let mut set1 = 0u32;
        let mut repeated = false;
        for c in line[i..i + len].chars() {
            let bit = 1 << (c as u32 - 'a' as u32);
            if bit & set1 == 0 {
                set1 |= bit;
            } else {
                repeated = true;
                break;
            }
        }
        if !repeated {
            answer = i + len;
            break;
        }
    }

    return answer;
}

fn main() -> Result<(), Box<dyn Error>> {
    let file = File::open("inputs/day6.txt")?;
    let line = io::BufReader::new(file)
        .lines()
        .nth(0)
        .unwrap()
        .unwrap()
        .to_owned();

    let answer1 = find_sequence(&line, 4);
    println!("Answer Part1: {}", answer1);

    let answer2 = find_sequence(&line, 14);
    println!("Answer Part2: {}", answer2);

    Ok(())
}