day(24): refactor the modular arithmetics
Signed-off-by: Matej Focko <me@mfocko.xyz>
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1 changed files with 34 additions and 24 deletions
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@ -39,31 +39,41 @@ impl Index<Position> for Basin {
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}
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// We need to account for the loops of the blizzards
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let x_mod = self.cols - 2;
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let y_mod = self.rows - 2;
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let width = self.cols - 2;
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let height = self.rows - 2;
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let x_w = ((index.x() - 1 + x_mod - (index.z() % x_mod)) % x_mod + 1) as usize;
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let x_e = ((index.x() - 1 + x_mod + (index.z() % x_mod)) % x_mod + 1) as usize;
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let y_n = ((index.y() - 1 + y_mod - (index.z() % y_mod)) % y_mod + 1) as usize;
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let y_s = ((index.y() - 1 + y_mod + (index.z() % y_mod)) % y_mod + 1) as usize;
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if self.map[index.y() as usize][x_w] == '>' {
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return &self.map[index.y() as usize][x_w];
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let blizzard_origin = |size, d, t, i| ((i - 1 + size + d * (t % size)) % size + 1) as usize;
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[
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(
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index.y() as usize,
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blizzard_origin(width, -1, index.z(), index.x()),
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'>',
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),
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(
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index.y() as usize,
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blizzard_origin(width, 1, index.z(), index.x()),
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'<',
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),
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(
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blizzard_origin(height, -1, index.z(), index.y()),
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index.x() as usize,
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'v',
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),
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(
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blizzard_origin(height, 1, index.z(), index.y()),
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index.x() as usize,
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'^',
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),
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]
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.iter()
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.find_map(|&(y, x, direction)| {
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if self.map[y][x] == direction {
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Some(&self.map[y][x])
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} else {
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None
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}
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if self.map[index.y() as usize][x_e] == '<' {
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return &self.map[index.y() as usize][x_e];
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}
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if self.map[y_n][index.x() as usize] == 'v' {
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return &self.map[y_n][index.x() as usize];
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}
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if self.map[y_s][index.x() as usize] == '^' {
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return &self.map[y_s][index.x() as usize];
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}
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&'.'
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})
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.unwrap_or(&'.')
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}
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}
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