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| 1 | +fn main() { |
| 2 | + let mut input = String::new(); |
| 3 | + std::io::stdin().read_line(&mut input).unwrap(); |
| 4 | + let mut directions = input.trim().chars().enumerate().cycle(); |
| 5 | + |
| 6 | + const WIDTH: usize = 7; |
| 7 | + const END: u64 = 1000000000000; |
| 8 | + |
| 9 | + let blocks = [ |
| 10 | + vec![(0, 0), (0, 1), (0, 2), (0, 3)], |
| 11 | + vec![(0, 1), (1, 0), (1, 1), (1, 2), (2, 1)], |
| 12 | + vec![(0, 0), (0, 1), (0, 2), (1, 2), (2, 2)], |
| 13 | + vec![(0, 0), (1, 0), (2, 0), (3, 0)], |
| 14 | + vec![(0, 0), (0, 1), (1, 0), (1, 1)], |
| 15 | + ]; |
| 16 | + |
| 17 | + let mut map = vec![[false; WIDTH]; 0]; |
| 18 | + let mut settled = 0u64; |
| 19 | + let mut block = 0; |
| 20 | + let mut pos = (3isize, 2isize); |
| 21 | + |
| 22 | + let mut cycle: Option<(u64, usize, usize, Vec<usize>)> = None; |
| 23 | + |
| 24 | + loop { |
| 25 | + let (dir_index, direction) = directions.next().unwrap(); |
| 26 | + let new_x = match direction { |
| 27 | + '<' => pos.1 - 1, |
| 28 | + '>' => pos.1 + 1, |
| 29 | + _ => panic!(), |
| 30 | + }; |
| 31 | + |
| 32 | + if new_x >= 0 && blocks[block].iter().all(|&(y, x)| { |
| 33 | + let (abs_y, abs_x) = (pos.0 as usize + y, new_x as usize + x); |
| 34 | + abs_x < WIDTH && (abs_y >= map.len() || !map[abs_y][abs_x]) |
| 35 | + }) { |
| 36 | + pos.1 = new_x; |
| 37 | + } |
| 38 | + |
| 39 | + let new_y = pos.0 - 1; |
| 40 | + if new_y < 0 || blocks[block].iter().any(|&(y, x)| { |
| 41 | + let (abs_y, abs_x) = (new_y as usize + y, pos.1 as usize + x); |
| 42 | + abs_y < map.len() && map[abs_y][abs_x] |
| 43 | + }) { |
| 44 | + for &(y, x) in &blocks[block] { |
| 45 | + let (abs_y, abs_x) = (pos.0 as usize + y, pos.1 as usize + x); |
| 46 | + while abs_y >= map.len() { |
| 47 | + map.push([false; WIDTH]); |
| 48 | + } |
| 49 | + map[abs_y][abs_x] = true; |
| 50 | + } |
| 51 | + |
| 52 | + pos = (map.len() as isize + 3, 2); |
| 53 | + block = (block + 1) % blocks.len(); |
| 54 | + settled += 1; |
| 55 | + |
| 56 | + if let Some((_, _, _, heights)) = &mut cycle { |
| 57 | + heights.push(map.len() - heights[0]); |
| 58 | + } |
| 59 | + |
| 60 | + if settled == END { |
| 61 | + println!("{}", map.len()); |
| 62 | + break; |
| 63 | + } else if map.last().map_or(false, |top| top.iter().all(|&x| x)) { |
| 64 | + if let Some((start_settled, start_block, start_dir_index, heights)) = &mut cycle { |
| 65 | + if block == *start_block && dir_index == *start_dir_index { |
| 66 | + let cycle_height_len = (map.len() - heights[0]) as u64; |
| 67 | + let cycle_settled_len = settled - *start_settled; |
| 68 | + let remaining_settled = END - settled; |
| 69 | + let remaining_cycles = remaining_settled / cycle_settled_len; |
| 70 | + let remaining_remainder = remaining_settled % cycle_settled_len; |
| 71 | + println!( |
| 72 | + "{}", |
| 73 | + map.len() as u64 + |
| 74 | + remaining_cycles * cycle_height_len + |
| 75 | + heights[remaining_remainder as usize] as u64, |
| 76 | + ); |
| 77 | + break; |
| 78 | + } |
| 79 | + } else { |
| 80 | + cycle = Some((settled, block, dir_index, vec![map.len()])); |
| 81 | + } |
| 82 | + } |
| 83 | + } else { |
| 84 | + pos.0 = new_y; |
| 85 | + } |
| 86 | + } |
| 87 | +} |
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