ddsk

main.rs

use std::fmt;
use std::io::{self, Read, Write};

#[derive(Clone, Copy)]
enum DdSk {
    Dodo,
    Suko,
}

impl DdSk {
    fn push(&self, state: &mut u16) {
        *state = state.overflowing_shl(1).0 | self.bit();
    }

    const fn bit(self) -> u16 {
        match self {
            DdSk::Dodo => 0x0000_0000,
            DdSk::Suko => 0x0000_0001,
        }
    }
}

impl From<bool> for DdSk {
    fn from(v: bool) -> Self {
        if (v as u16) == DdSk::Suko.bit() { DdSk::Suko } else { DdSk::Dodo }
    }
}

impl fmt::Display for DdSk {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            DdSk::Dodo => f.write_str("ドド"),
            DdSk::Suko => f.write_str("スコ"),
        }
    }
}

fn bits(v: u8) -> [bool; 8] {
    return [
        (v >> 7) & 0b0000_0001 == 0b0000_0000,
        (v >> 6) & 0b0000_0001 == 0b0000_0000,
        (v >> 5) & 0b0000_0001 == 0b0000_0000,
        (v >> 4) & 0b0000_0001 == 0b0000_0000,
        (v >> 3) & 0b0000_0001 == 0b0000_0000,
        (v >> 2) & 0b0000_0001 == 0b0000_0000,
        (v >> 1) & 0b0000_0001 == 0b0000_0000,
        (v >> 0) & 0b0000_0001 == 0b0000_0000,
    ];
}

fn main() -> io::Result<()> {
    let wants = [
        DdSk::Dodo, DdSk::Suko, DdSk::Suko, DdSk::Suko,
        DdSk::Dodo, DdSk::Suko, DdSk::Suko, DdSk::Suko,
        DdSk::Dodo, DdSk::Suko, DdSk::Suko, DdSk::Suko,
    ];
    let wants_mask: u16 = wants.into_iter().map(|_| 1).reduce(|l, r| (l << 1) | r).unwrap();
    let wants = wants.into_iter().map(DdSk::bit).reduce(|l, r| (l << 1) | r).unwrap();

    let mut fd0 = io::BufReader::new(io::stdin().lock());
    let mut fd1 = io::BufWriter::new(io::stdout().lock());

    let mut buf = [0u8];
    let mut state = 0b0000_0000u16;
    loop {
        fd0.read_exact(&mut buf)?;
        for ddsk in bits(buf[0]).into_iter().map(DdSk::from) {
            ddsk.push(&mut state);
            write!(&mut fd1, "{}", ddsk)?;
            if (state & wants_mask) == wants {
                writeln!(&mut fd1, "ラブ注入♡")?;
                return Ok(())
            }
        }
    }
}