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Refactor out common code

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This commit is contained in:
Bert Peters
2022-12-12 22:46:30 +01:00
parent e2d1ec8c91
commit f8c6f4e01f
1 changed files with 19 additions and 49 deletions
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68
2022/src/day12.rs
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@@ -14,7 +14,12 @@ fn can_travel(from: u8, to: u8) -> bool {
}
}
pub fn part1(input: &[u8]) -> Result<String> {
fn parts_common(
input: &[u8],
starting_symbol: u8,
is_end: impl Fn(u8) -> bool,
accessible: impl Fn(u8, u8) -> bool,
) -> Result<String> {
let width = input
.iter()
.position(|&c| c == b'\n')
@@ -23,7 +28,7 @@ pub fn part1(input: &[u8]) -> Result<String> {
let starting_pos = input
.iter()
.position(|&c| c == b'S')
.position(|&c| c == starting_symbol)
.context("Could not find starting position")?;
let mut visited = IndexSet::with_capacity(input.len());
@@ -32,12 +37,12 @@ pub fn part1(input: &[u8]) -> Result<String> {
todo.push_back((0, starting_pos));
while let Some((dist, pos)) = todo.pop_front() {
if input[pos] == b'E' {
if is_end(input[pos]) {
return Ok(dist.to_string());
}
let mut add_todo = |new: usize| {
if can_travel(input[pos], input[new]) && visited.insert(new) {
if accessible(input[pos], input[new]) && visited.insert(new) {
todo.push_back((dist + 1, new));
}
};
@@ -62,52 +67,17 @@ pub fn part1(input: &[u8]) -> Result<String> {
anyhow::bail!("Did not find a valid route")
}
pub fn part1(input: &[u8]) -> Result<String> {
parts_common(input, b'S', |b| b == b'E', can_travel)
}
pub fn part2(input: &[u8]) -> Result<String> {
let width = input
.iter()
.position(|&c| c == b'\n')
.context("No newlines in input")?
+ 1;
let starting_pos = input
.iter()
.position(|&c| c == b'E')
.context("Could not find starting position")?;
let mut visited = IndexSet::with_capacity(input.len());
let mut todo = VecDeque::new();
todo.push_back((0, starting_pos));
while let Some((dist, pos)) = todo.pop_front() {
if input[pos] == b'a' || input[pos] == b'S' {
return Ok(dist.to_string());
}
let mut add_todo = |new: usize| {
if can_travel(input[new], input[pos]) && visited.insert(new) {
todo.push_back((dist + 1, new));
}
};
if pos % width != 0 {
add_todo(pos - 1);
}
if pos % width != width - 1 {
add_todo(pos + 1);
}
if pos >= width {
add_todo(pos - width);
}
if pos + width < input.len() {
add_todo(pos + width);
}
}
anyhow::bail!("Did not find a valid route")
parts_common(
input,
b'E',
|b| b == b'a' || b == b'S',
|a, b| can_travel(b, a),
)
}
#[cfg(test)]