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use std::io;
use std::io::BufRead;
use std::cmp::min;
use std::mem::swap;
fn bits_to_u8(bits: &[u8]) -> u8 {
(0..min(bits.len(), 8)).map(|i| if bits[i] == '#' as u8 { 1 << i } else { 0 }).sum()
}
fn getbit(bits: &[u8], idx: usize) -> u8 {
(bits[idx / 8] & 1 << idx % 8) >> idx % 8
}
fn evolve(board: &[u8], out: &mut [u8], patdict: &[u8; 1 << 5]) {
assert!(board.len() == out.len());
let mut pat = board[0] & 0x1f;
for i in 2..8*out.len()-2 {
let bit = patdict[pat as usize];
// for i in 0..5 { print!("{}", if (pat & 1 << i) != 0 { '#' } else { '.' }); }
// println!(" {}", bit);
out[i / 8] = out[i / 8] & !(1 << i % 8) | bit << i % 8;
if i == 8 * out.len() - 3 { break; }
pat = pat >> 1 | getbit(board, i + 3) << 4;
}
}
#[allow(dead_code)]
fn print_board(board: &[u8]) {
for i in 0..8*board.len() {
let bit = board[i / 8] & (1 << (i % 8));
print!("{}", if bit != 0 { '#' } else { '.' });
}
println!("");
}
fn board_sum(board: &[u8], zeroidx: i64) -> i64 {
let mut numsum = 0;
for i in 0..8*board.len() {
if (board[i / 8] & 1 << i % 8) != 0 {
numsum += i as i64 - 8 * zeroidx as i64;
}
}
numsum
}
fn make_board(init_str: &str, niters: usize) -> (Vec<u8>, usize) {
let slack = 2 * niters + 2;
let zeroidx = (slack + 7) / 8;
let mut board = vec![0; zeroidx + (init_str.len() + slack + 7) / 8];
for i in 0..(init_str.len() + 7) / 8 {
board[zeroidx + i] = bits_to_u8(&init_str.as_bytes()[8*i..min(8*i+8, init_str.len())]);
}
(board, zeroidx)
}
struct Repetition {
generation: usize,
score: i64,
increment: i64,
}
fn findrep(init_str: &str, patdict: &[u8; 1 << 5]) -> Repetition {
let niters = 1000;
let (mut board, zeroidx) = make_board(init_str, niters);
let mut board2 = vec![0; board.len()];
let mut prevscore = 0;
let mut previncr = 0;
let mut streak = 0;
for generation in 1..niters+1 {
evolve(&board, &mut board2, &patdict);
swap(&mut board, &mut board2);
let score = board_sum(&board, zeroidx as i64);
let increment = score - prevscore;
if increment == previncr {
streak += 1;
if streak > 10 {
return Repetition { generation, score, increment };
}
} else {
streak = 0;
}
prevscore = score;
previncr = increment;
}
unreachable!();
}
fn simulate(init_str: &str, niters: usize, patdict: &[u8; 1 << 5]) -> i64 {
let (mut board, zeroidx) = make_board(init_str, niters);
let mut board2 = vec![0; board.len()];
for _ in 0..niters {
evolve(&board, &mut board2, &patdict);
swap(&mut board, &mut board2);
}
board_sum(&board, zeroidx as i64)
}
pub fn main<T: BufRead>(reader: T) -> io::Result<(String, String)> {
let mut lines_iter = reader.lines();
let init_str = &lines_iter.next().unwrap().unwrap().clone()[15..];
let patdict = {
let mut patdict = [0; 1 << 5];
lines_iter.next();
for line in lines_iter {
let line = line.unwrap();
let pat = bits_to_u8(&line.as_bytes()[0..5]);
let res = bits_to_u8(&line.as_bytes()[9..10]);
patdict[pat as usize] = res;
}
patdict
};
let part1 = simulate(&init_str, 20, &patdict).to_string();
let rep = findrep(&init_str, &patdict);
let part2 = (rep.score + (50000000000 - rep.generation as i64) * rep.increment).to_string();
Ok((part1, part2))
}
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