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| 1 | +use utils::point::Point2D; |
| 2 | +use utils::prelude::*; |
| 3 | + |
| 4 | +/// Recognizing text formed by converging points. |
| 5 | +#[derive(Clone, Debug)] |
| 6 | +pub struct Day10 { |
| 7 | + message: String, |
| 8 | + seconds: u32, |
| 9 | +} |
| 10 | + |
| 11 | +impl Day10 { |
| 12 | + pub fn new(input: &str, _: InputType) -> Result<Self, InputError> { |
| 13 | + let point = parser::i32() |
| 14 | + .with_prefix(parser::take_while(|&x| x == b' ')) |
| 15 | + .repeat_n(b',') |
| 16 | + .map(Point2D::from); |
| 17 | + |
| 18 | + let mut points = point |
| 19 | + .with_prefix("position=<") |
| 20 | + .with_suffix("> velocity=<") |
| 21 | + .then(point) |
| 22 | + .with_suffix(">") |
| 23 | + .repeat(parser::eol(), 2) |
| 24 | + .parse_complete(input)?; |
| 25 | + |
| 26 | + let mut seconds = 0; |
| 27 | + let (mut last_x_diff, mut last_y_diff) = (i32::MAX, i32::MAX); |
| 28 | + let message = 'time: loop { |
| 29 | + let (mut min_x, mut max_x) = (i32::MAX, i32::MIN); |
| 30 | + let (mut min_y, mut min_y_vel, mut max_y, mut max_y_vel) = (i32::MAX, 0, i32::MIN, 0); |
| 31 | + for (p, v) in &points { |
| 32 | + min_x = min_x.min(p.x); |
| 33 | + max_x = max_x.max(p.x); |
| 34 | + |
| 35 | + if p.y < min_y { |
| 36 | + min_y = p.y; |
| 37 | + min_y_vel = v.y; |
| 38 | + } |
| 39 | + if p.y > max_y { |
| 40 | + max_y = p.y; |
| 41 | + max_y_vel = v.y; |
| 42 | + } |
| 43 | + } |
| 44 | + |
| 45 | + let (x_diff, y_diff) = (max_x.saturating_sub(min_x), max_y.saturating_sub(min_y)); |
| 46 | + if x_diff > last_x_diff |
| 47 | + || y_diff > last_y_diff |
| 48 | + || (x_diff == last_x_diff && y_diff == last_y_diff) |
| 49 | + { |
| 50 | + return Err(InputError::new(input, 0, "points never converge")); |
| 51 | + } |
| 52 | + (last_x_diff, last_y_diff) = (x_diff, y_diff); |
| 53 | + |
| 54 | + // Letters are 6 wide and 10 tall, with 2 wide gaps between them |
| 55 | + if y_diff != 9 || x_diff % 8 != 5 { |
| 56 | + let advance_by = if y_diff >= 10 && min_y_vel.saturating_sub(max_y_vel) > 0 { |
| 57 | + ((y_diff - 9) / min_y_vel.saturating_sub(max_y_vel)).max(1) |
| 58 | + } else { |
| 59 | + 1 |
| 60 | + }; |
| 61 | + |
| 62 | + for (p, v) in points.iter_mut() { |
| 63 | + *p += *v * advance_by; |
| 64 | + } |
| 65 | + seconds += advance_by as u32; |
| 66 | + |
| 67 | + continue; |
| 68 | + } |
| 69 | + |
| 70 | + let len = ((max_x - min_x + 3) / 8) as usize; |
| 71 | + let mut letters = vec![0u64; len]; |
| 72 | + for (p, _) in points.iter() { |
| 73 | + if (p.x - min_x) % 8 >= 6 { |
| 74 | + // Point where there should be a 2-wide gap |
| 75 | + continue 'time; |
| 76 | + } |
| 77 | + |
| 78 | + letters[(p.x - min_x) as usize / 8] |= |
| 79 | + 1 << (59 - ((p.x - min_x) % 8 + 6 * (p.y - min_y))); |
| 80 | + } |
| 81 | + break letters.into_iter().map(Self::ocr).collect::<String>(); |
| 82 | + }; |
| 83 | + |
| 84 | + Ok(Self { message, seconds }) |
| 85 | + } |
| 86 | + |
| 87 | + fn ocr(letter: u64) -> char { |
| 88 | + // ## ##### #### ###### ###### #### # # ### # # # # # |
| 89 | + // # # # # # # # # # # # # # # # # ## # |
| 90 | + // # # # # # # # # # # # # # # ## # |
| 91 | + // # # # # # # # # # # # # # # # # # |
| 92 | + // # # ##### # ##### ##### # ###### # ## # # # # |
| 93 | + // ###### # # # # # # ### # # # ## # # # # |
| 94 | + // # # # # # # # # # # # # # # # # # # |
| 95 | + // # # # # # # # # # # # # # # # # # ## |
| 96 | + // # # # # # # # # # ## # # # # # # # # ## |
| 97 | + // # # ##### #### ###### # ### # # # ### # # ###### # # |
| 98 | + // |
| 99 | + // ##### ##### # # ###### |
| 100 | + // # # # # # # # |
| 101 | + // # # # # # # # |
| 102 | + // # # # # # # # |
| 103 | + // ##### ##### ## # |
| 104 | + // # # # ## # |
| 105 | + // # # # # # # |
| 106 | + // # # # # # # |
| 107 | + // # # # # # # |
| 108 | + // # # # # # ###### |
| 109 | + match letter { |
| 110 | + //000000111111222222333333444444555555666666777777888888999999 |
| 111 | + 0b001100010010100001100001100001111111100001100001100001100001 => 'A', |
| 112 | + 0b111110100001100001100001111110100001100001100001100001111110 => 'B', |
| 113 | + 0b011110100001100000100000100000100000100000100000100001011110 => 'C', |
| 114 | + 0b111111100000100000100000111110100000100000100000100000111111 => 'E', |
| 115 | + 0b111111100000100000100000111110100000100000100000100000100000 => 'F', |
| 116 | + 0b011110100001100000100000100000100111100001100001100011011101 => 'G', |
| 117 | + 0b100001100001100001100001111111100001100001100001100001100001 => 'H', |
| 118 | + 0b000111000010000010000010000010000010000010100010100010011100 => 'J', |
| 119 | + 0b100001100010100100101000110000110000101000100100100010100001 => 'K', |
| 120 | + 0b100000100000100000100000100000100000100000100000100000111111 => 'L', |
| 121 | + 0b100001110001110001101001101001100101100101100011100011100001 => 'N', |
| 122 | + 0b111110100001100001100001111110100000100000100000100000100000 => 'P', |
| 123 | + 0b111110100001100001100001111110100100100010100010100001100001 => 'R', |
| 124 | + 0b100001100001010010010010001100001100010010010010100001100001 => 'X', |
| 125 | + 0b111111000001000001000010000100001000010000100000100000111111 => 'Z', |
| 126 | + _ => Self::unknown_letter(letter), |
| 127 | + } |
| 128 | + } |
| 129 | + |
| 130 | + #[cold] |
| 131 | + fn unknown_letter(letter: u64) -> char { |
| 132 | + let mut display = String::new(); |
| 133 | + for b in (0..60).rev() { |
| 134 | + display.push(if letter & (1 << b) == 0 { ' ' } else { '#' }); |
| 135 | + if b % 6 == 0 { |
| 136 | + display.push('\n'); |
| 137 | + } |
| 138 | + } |
| 139 | + panic!("unknown letter {letter:#062b}:\n{display}"); |
| 140 | + } |
| 141 | + |
| 142 | + #[must_use] |
| 143 | + pub fn part1(&self) -> &str { |
| 144 | + &self.message |
| 145 | + } |
| 146 | + |
| 147 | + #[must_use] |
| 148 | + pub fn part2(&self) -> u32 { |
| 149 | + self.seconds |
| 150 | + } |
| 151 | +} |
| 152 | + |
| 153 | +examples!(Day10 -> (&'static str, u32) []); |
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