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Painfully implement day 22 part 2

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Bert Peters
2023-11-12 14:32:22 +01:00
parent 10174a2915
commit 542a8143e2
1 changed files with 106 additions and 6 deletions
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112
2022/src/day22.rs
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@@ -139,7 +139,7 @@ pub fn part1(input: &[u8]) -> Result<String> {
let (map, steps) = parse_input(input, parse_map)?;
let mut dir = Direction::Right;
let mut y = 0;
let mut x = find_starting_x(&map[y])?;
let mut x = find_starting_x(map[y])?;
for step in steps {
match step {
@@ -278,23 +278,123 @@ pub fn part2(input: &[u8]) -> Result<String> {
let squares = break_squares(&map, side_length);
let convert_coords = |square: usize, x: usize, y: usize| {
let offset_x = squares[square].1 * side_length + x + 1;
let offset_y = squares[square].2 * side_length + y + 1;
(offset_x, offset_y)
};
let mut current_square = 0;
let mut y = 0;
let mut x = find_starting_x(&squares[current_square].0[y])?;
let mut x = find_starting_x(squares[current_square].0[y])?;
let mut dir = Direction::Right;
for step in steps {
match step {
Step::Left => dir = dir.turn_left(),
Step::Right => dir = dir.turn_right(),
Step::Forward(amount) => anyhow::bail!("not implemented"),
Step::Forward(mut amount) => {
'outer: while amount > 0 {
let map = &squares[current_square].0;
// Need to allow unused range bound, since we're actually tracking how much we
// still have to do. The loops are expected to end early, and we should remember
// how much work we've actually done.
#[allow(clippy::mut_range_bound)]
let coord = match dir {
Direction::Up => {
for _ in 0..amount {
if y == 0 {
break;
} else if map[y - 1][x] == b'#' {
break 'outer;
} else {
y -= 1;
}
}
x
}
Direction::Down => {
for _ in 0..amount {
if y + 1 >= side_length {
break;
} else if map[y + 1][x] == b'#' {
break 'outer;
} else {
amount -= 1;
y += 1;
}
}
x
}
Direction::Left => {
for _ in 0..amount {
if x == 0 {
break;
} else if map[y][x - 1] == b'#' {
break 'outer;
} else {
x -= 1;
amount -= 1;
}
}
y
}
Direction::Right => {
for _ in 0..amount {
if x + 1 >= side_length {
break;
} else if map[y][x + 1] == b'#' {
break 'outer;
} else {
amount -= 1;
x += 1;
}
}
y
}
};
if amount > 0 {
let (new_dir, new_square, invert) =
TRANSITIONS[current_square][dir as usize];
let flipped_coord = if invert {
side_length - 1 - coord
} else {
coord
};
let (new_x, new_y) = match new_dir {
Direction::Up => (flipped_coord, side_length - 1),
Direction::Down => (flipped_coord, 0),
Direction::Left => (side_length - 1, flipped_coord),
Direction::Right => (0, flipped_coord),
};
if squares[new_square].0[new_y][new_x] == b'#' {
break 'outer;
}
x = new_x;
y = new_y;
current_square = new_square;
dir = new_dir;
amount -= 1;
}
}
}
}
}
let real_x = x + squares[current_square].1 * side_length;
let real_y = y + squares[current_square].2 * side_length;
let (real_x, real_y) = convert_coords(current_square, x, y);
Ok((1000 * (real_y + 1) + 4 * (real_x + 1) + dir as usize).to_string())
Ok((1000 * real_y + 4 * real_x + dir as usize).to_string())
}
#[cfg(test)]