Day8

Author: hukasu

Cargo.toml

@@ -6,5 +6,6 @@ members = [
     "day4",
     "day5",
     "day6",
-    "day7"
+    "day7",
+    "day8"
 ]

day8/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "advent_of_code_2022_day8"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day8/examples/advent_input.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let res = advent_of_code_2022_day8::count_visible_trees("./day8/resources/input.txt");
+    println!("{:?}", res)
+}

day8/examples/advent_input_part2.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let res = advent_of_code_2022_day8::find_best_scenic_score("./day8/resources/input.txt");
+    println!("{:?}", res)
+}

day8/resources/input.txt

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day8/src/lib.rs

@@ -0,0 +1,212 @@
+enum ShadowDirection {
+    North,
+    South,
+    East,
+    West
+}
+
+fn is_shadowed_bidirectional(a: &Vec<Vec<bool>>, b: &Vec<Vec<bool>>) -> Vec<Vec<bool>> {
+    a.iter()
+        .zip(b)
+        .map(
+            |(n, s)| {
+                n.iter().zip(s)
+                    .map(|(n, s)| *n || *s)
+                    .collect()
+            }
+        )
+        .collect()
+}
+
+fn build_shadow_map(tree_matrix: &Vec<Vec<u32>>, direction: ShadowDirection) -> Vec<Vec<bool>> {
+    let mut shadow_height = tree_matrix.clone();
+    let mut res = vec![vec![true; tree_matrix[0].len()]; tree_matrix.len()];
+    
+    match direction {
+        ShadowDirection::North => {
+            for i in (0..(tree_matrix.len() - 1)).rev() {
+                for j in 0..(tree_matrix[0].len()) {
+                    res[i][j] = shadow_height[i][j].cmp(&shadow_height[i + 1][j]) == std::cmp::Ordering::Greater;
+                    shadow_height[i][j] = (shadow_height[i + 1][j]).max(shadow_height[i][j]);
+                }
+            }
+        },
+        ShadowDirection::South => {
+            for i in 1..(tree_matrix.len()) {
+                for j in 0..(tree_matrix[0].len()) {
+                    res[i][j] = shadow_height[i][j].cmp(&shadow_height[i - 1][j]) == std::cmp::Ordering::Greater;
+                    shadow_height[i][j] = (shadow_height[i - 1][j]).max(shadow_height[i][j]);
+                }
+            }
+        },
+        ShadowDirection::East => {
+            for i in 0..(tree_matrix.len()) {
+                for j in 1..(tree_matrix[0].len()) {
+                    res[i][j] = shadow_height[i][j].cmp(&shadow_height[i][j - 1]) == std::cmp::Ordering::Greater;
+                    shadow_height[i][j] = (shadow_height[i][j - 1]).max(shadow_height[i][j]);
+                }
+            }
+        },
+        ShadowDirection::West => {
+            for i in 0..(tree_matrix.len()) {
+                for j in (0..(tree_matrix[0].len() - 1)).rev() {
+                    res[i][j] = shadow_height[i][j].cmp(&shadow_height[i][j + 1]) == std::cmp::Ordering::Greater;
+                    shadow_height[i][j] = (shadow_height[i][j + 1]).max(shadow_height[i][j]);
+                }
+            }
+        },
+    }
+
+    res
+}
+
+fn build_tree_height_matrix(tree_heights: &str) -> Vec<Vec<u32>> {
+    tree_heights.lines()
+        .map(
+            |l| l.chars()
+                .map(|c| c.to_digit(10).unwrap())
+                .collect()
+        )
+        .collect()
+}
+
+fn _count_visible_trees(tree_heights: &str) -> u32 {
+    let tree_matrix = build_tree_height_matrix(tree_heights);
+    // Vectors represent which trees are visible when looking at a certain direction
+    let north_shadow = build_shadow_map(&tree_matrix, ShadowDirection::North);
+    let south_shadow = build_shadow_map(&tree_matrix, ShadowDirection::South);
+    let east_shadow = build_shadow_map(&tree_matrix, ShadowDirection::East);
+    let west_shadow = build_shadow_map(&tree_matrix, ShadowDirection::West);
+
+    let visible_north_south = is_shadowed_bidirectional(&north_shadow, &south_shadow);
+    let visible_east_west = is_shadowed_bidirectional(&east_shadow, &west_shadow);
+
+    let visible = is_shadowed_bidirectional(&visible_north_south, &visible_east_west);
+    
+    let shadowed = visible.iter()
+        .flatten()
+        .filter(|b| **b)
+        .count();
+    (shadowed) as u32
+}
+
+pub fn count_visible_trees(input_path: &str) -> u32 {
+    let content = std::fs::read_to_string(input_path);
+    match content {
+        Ok(content) => _count_visible_trees(&content),
+        Err(er) => {
+            println!("{}", er);
+            0
+        }
+    }
+}
+
+fn count_view_north(tree_matrix: &Vec<Vec<u32>>, x: usize, y: usize) -> u32 {
+    let mut count = 0;
+    for tx in (0..x).rev() {
+        count = count + 1;
+        if tree_matrix[x][y] <= tree_matrix[tx][y] {
+            break;
+        }
+    }
+    count
+}
+
+fn count_view_south(tree_matrix: &Vec<Vec<u32>>, x: usize, y: usize) -> u32 {
+    let mut count = 0;
+    for tx in (x + 1)..(tree_matrix.len()) {
+        count = count + 1;
+        if tree_matrix[x][y] <= tree_matrix[tx][y] {
+            break;
+        }
+    }
+    count
+}
+
+fn count_view_east(tree_matrix: &Vec<Vec<u32>>, x: usize, y: usize) -> u32 {
+    let mut count = 0;
+    for ty in (y + 1)..(tree_matrix[0].len()) {
+        count = count + 1;
+        if tree_matrix[x][y] <= tree_matrix[x][ty] {
+            break;
+        }
+    }
+    count
+}
+
+fn count_view_west(tree_matrix: &Vec<Vec<u32>>, x: usize, y: usize) -> u32 {
+    let mut count = 0;
+    for ty in (0..y).rev() {
+        count = count + 1;
+        if tree_matrix[x][y] <= tree_matrix[x][ty] {
+            break;
+        }
+    }
+    count
+}
+
+fn tree_scenic_score(tree_matrix: &Vec<Vec<u32>>, x: usize, y: usize) -> u32 {
+    count_view_north(tree_matrix, x, y) *
+    count_view_south(tree_matrix, x, y) *
+    count_view_east(tree_matrix, x, y) *
+    count_view_west(tree_matrix, x, y)
+}
+
+fn _find_best_scenic_score(tree_heights: &str) -> u32 {
+    let tree_matrix = build_tree_height_matrix(tree_heights);
+    tree_matrix.iter().enumerate()
+        .map(
+            |(x, v)| {
+                v.iter().enumerate()
+                    .map(
+                        |(y, _)| {
+                            tree_scenic_score(&tree_matrix, x, y)
+                        }
+                    )
+                    .max()
+                    .unwrap_or(0)
+            }
+        )
+        .max()
+        .unwrap_or(0)
+}
+
+pub fn find_best_scenic_score(input_path: &str) -> u32 {
+    let content = std::fs::read_to_string(input_path);
+    match content {
+        Ok(content) => _find_best_scenic_score(&content),
+        Err(er) => {
+            println!("{}", er);
+            0
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INP1: &str = 
+r#"30373
+25512
+65332
+33549
+35390"#;
+
+    #[test]
+    fn test_input1() {
+        assert_eq!(_count_visible_trees(TEST_INP1), 21)
+    }
+
+    #[test]
+    fn test_input1_part2_test1() {
+        let tree_matrix = build_tree_height_matrix(TEST_INP1);
+        assert_eq!(tree_scenic_score(&tree_matrix, 1, 2), 4)
+    }
+
+    #[test]
+    fn test_input1_part2_test2() {
+        let tree_matrix = build_tree_height_matrix(TEST_INP1);
+        assert_eq!(tree_scenic_score(&tree_matrix, 3, 2), 8)
+    }
+}