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2022 day 8 part 2

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This commit is contained in:
Maciej Jur 2022-12-08 12:23:10 +01:00
parent 145b112dd7
commit 70308da959
1 changed files with 35 additions and 43 deletions
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78
2022/rust/src/solutions/day08.rs
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@ -64,22 +64,6 @@ fn solve1(data: &[Vec<i32>]) -> usize {
create_mask(data).into_iter().map(|row| row.iter().filter(|&e| *e).count()).sum() create_mask(data).into_iter().map(|row| row.iter().filter(|&e| *e).count()).sum()
} }
#[inline(always)]
fn find_limit(
data: &[Vec<i32>],
last_heights: &mut HashMap<i32, usize>,
row: usize,
col: usize
) -> usize {
let mut limit = 0;
for h in data[row][col]..=9 {
if let Some(since) = last_heights.get(&h) {
limit = max(limit, *since);
}
};
limit
}
fn find_scores(data: &[Vec<i32>]) -> Vec<Vec<i32>> { fn find_scores(data: &[Vec<i32>]) -> Vec<Vec<i32>> {
let rows = data.len(); let rows = data.len();
let cols = data[0].len(); let cols = data[0].len();
@ -90,34 +74,39 @@ fn find_scores(data: &[Vec<i32>]) -> Vec<Vec<i32>> {
.collect(); .collect();
for row in 0..rows { for row in 0..rows {
let mut last_heights: HashMap<i32, usize> = HashMap::new();
for col in 0..cols { for col in 0..cols {
let limit = find_limit(data, &mut last_heights, row, col); let mut score = 1;
scores[row][col] = scores[row][col] * (col - limit) as i32; let current = data[row][col];
last_heights.insert(data[row][col], col);
};
let mut last_heights: HashMap<i32, usize> = HashMap::new();
for col in (0..cols).rev() {
let limit = find_limit(data, &mut last_heights, row, col);
let limit = if limit == 0 { cols - 1 } else { limit };
scores[row][col] = scores[row][col] * (limit - col) as i32;
last_heights.insert(data[row][col], col);
};
};
for col in 0..cols { let mut temp = 0;
let mut last_heights: HashMap<i32, usize> = HashMap::new(); for c in (0..col).rev() {
for row in 0..rows { temp += 1;
let limit = find_limit(data, &mut last_heights, row, col); if data[row][c] >= current { break };
scores[row][col] = scores[row][col] * (row - limit) as i32; }
last_heights.insert(data[row][col], row); score *= temp;
};
let mut last_heights: HashMap<i32, usize> = HashMap::new(); let mut temp = 0;
for row in (0..cols).rev() { for c in (col+1)..cols {
let limit = find_limit(data, &mut last_heights, row, col); temp += 1;
let limit = if limit == 0 { rows - 1 } else { limit }; if data[row][c] >= current { break };
scores[row][col] = scores[row][col] * (limit - row) as i32; }
last_heights.insert(data[row][col], row); score *= temp;
let mut temp = 0;
for r in (0..row).rev() {
temp += 1;
if data[r][col] >= current { break };
}
score *= temp;
let mut temp = 0;
for r in (row+1)..rows {
temp += 1;
if data[r][col] >= current { break };
}
score *= temp;
scores[row][col] = score;
}; };
}; };
@ -128,7 +117,10 @@ fn solve2(data: &[Vec<i32>]) -> i32 {
let scores = find_scores(data); let scores = find_scores(data);
let reducer = |a, b| max(a, b); let reducer = |a, b| max(a, b);
scores.into_iter().map(|row| row.iter().copied().reduce(reducer).unwrap()).reduce(reducer).unwrap() scores.into_iter()
.map(|row| row.iter().copied().reduce(reducer).unwrap())
.reduce(reducer)
.unwrap()
} }