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Optimize 2020/03

This commit is contained in:
kageru 2020-12-04 11:08:06 +01:00
parent b96d15bd46
commit d7b71e32d9
Signed by: kageru
GPG Key ID: 8282A2BEA4ADA3D2
1 changed files with 15 additions and 5 deletions
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20
2020/03/src/main.rs
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@ -43,10 +43,17 @@ fn count_all_paths(forest: &Forest) -> usize {
}
fn count_trees(forest: &Forest, step_right: usize, step_down: usize) -> usize {
iter::successors(Some((0, 0)), |(y, x)| Some((y + step_down, (x + step_right) % forest[0].len())))
.map_while(|(y, x)| forest.get(y).map(|r| r[x]))
.filter(|&t| t == Tile::Tree)
.count()
iter::successors(Some((0, 0)), |(y, x)| {
Some((
y + step_down,
Some(x + step_right)
.filter(|&it| it < forest[0].len())
.unwrap_or((x + step_right) - forest[0].len()),
))
})
.map_while(|(y, x)| forest.get(y).map(|r| r[x]))
.filter(|&t| t == Tile::Tree)
.count()
}
fn main() {
@ -82,7 +89,10 @@ mod tests {
while y < forest.len() {
trees += (forest[y][x] == Tile::Tree) as usize;
y += step_down;
x = (x + step_right) % width;
x = x + step_right;
if x >= width {
x -= width;
}
}
return trees;
}