day 8 solution

2022/day8.txt

@@ -0,0 +1,99 @@
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2022/src/days/day8.rs

@@ -0,0 +1,209 @@
+use anyhow::Result;
+use std::fs;
+
+type World = [[u8; 100]; 100];
+type Visible = [[bool; 100]; 100];
+
+pub fn run() -> Result<()> {
+    #[cfg(not(feature = "test_input"))]
+    let file_contents = fs::read_to_string("day8.txt")?;
+
+    #[cfg(feature = "test_input")]
+    let file_contents = fs::read_to_string("tests/day8.txt")?;
+
+    let mut world: World = [[0; 100]; 100];
+
+    let mut size = 0;
+    for (row, line) in file_contents.lines().enumerate() {
+        size = row;
+        for (col, x) in line.chars().enumerate() {
+            world[row][col] = x.to_digit(10).expect("invalid digit") as u8;
+        }
+    }
+    size += 1;
+    println!("world size {}", size);
+    for row in world.iter().take(size) {
+        for col in row.iter().take(size) {
+            print!("{}", *col);
+        }
+        println!();
+    }
+
+    let mut visible: Visible = [[false; 100]; 100];
+    println!(
+        "part one {}",
+        part_one_visibility(&world, size, &mut visible)
+    );
+    println!("part two {}", part_two_score(&world, size, &visible));
+
+    Ok(())
+}
+
+fn part_one_visibility(world: &World, max_size: usize, visible: &mut Visible) -> usize {
+    for i in 0..max_size {
+        visible[i][max_size - 1] = true;
+        visible[i][0] = true;
+        visible[0][i] = true;
+        visible[max_size - 1][i] = true;
+    }
+
+    biggest_top(world, max_size, visible);
+    biggest_bottom(world, max_size, visible);
+    biggest_left(world, max_size, visible);
+    biggest_right(world, max_size, visible);
+
+    println!("visible trees");
+    let mut count: usize = 0;
+    for row in visible.iter().take(max_size) {
+        for col in row.iter().take(max_size) {
+            if *col {
+                count += 1;
+                print!("1");
+            } else {
+                print!("0");
+            }
+        }
+        println!();
+    }
+
+    count
+}
+
+fn part_two_score(world: &World, max_size: usize, visible: &Visible) -> usize {
+    let mut score: usize = 0;
+
+    for row in 1..(max_size - 1) {
+        for col in 1..(max_size - 1) {
+            if visible[row][col] {
+                let new_score = get_visibility_score(world, max_size, row, col);
+                if new_score > score {
+                    score = new_score;
+                }
+            }
+        }
+    }
+
+    score
+}
+
+fn get_visibility_score(world: &World, max_size: usize, row: usize, col: usize) -> usize {
+    let height = world[row][col];
+
+    let mut north: usize = 0;
+    for k in (0..row).rev() {
+        if world[k][col] < height {
+            north += 1;
+        } else if world[k][col] >= height {
+            north += 1;
+            break;
+        } else {
+            break;
+        }
+    }
+
+    let mut south: usize = 0;
+    for i in (row + 1)..max_size {
+        if world[i][col] < height {
+            south += 1;
+        } else if world[i][col] >= height {
+            south += 1;
+            break;
+        } else {
+            break;
+        }
+    }
+
+    let mut west: usize = 0;
+    for k in (0..col).rev() {
+        if world[row][k] < height {
+            west += 1;
+        } else if world[row][k] >= height {
+            west += 1;
+            break;
+        } else {
+            break;
+        }
+    }
+
+    let mut east: usize = 0;
+    for i in (col + 1)..max_size {
+        if world[row][i] < height {
+            east += 1;
+        } else if world[row][i] >= height {
+            east += 1;
+            break;
+        } else {
+            break;
+        }
+    }
+
+    north * south * east * west
+}
+
+fn biggest_left(world: &World, max_size: usize, visible: &mut Visible) {
+    let mut sizes: [u8; 100] = [0; 100];
+
+    for i in 0..max_size {
+        sizes[i] = world[i][0];
+    }
+
+    for row in 1..max_size {
+        for col in 1..max_size {
+            if world[row][col] > sizes[row] {
+                visible[row][col] = true;
+                sizes[row] = world[row][col];
+            }
+        }
+    }
+}
+
+fn biggest_right(world: &World, max_size: usize, visible: &mut Visible) {
+    let mut sizes: [u8; 100] = [0; 100];
+
+    for i in 0..max_size {
+        sizes[i] = world[i][max_size];
+    }
+
+    for row in 1..max_size {
+        for j in 1..max_size {
+            let col = max_size - j;
+            if world[row][col] > sizes[row] {
+                visible[row][col] = true;
+                sizes[row] = world[row][col];
+            }
+        }
+    }
+}
+
+fn biggest_top(world: &World, max_size: usize, visible: &mut Visible) {
+    let mut sizes: [u8; 100] = [0; 100];
+
+    sizes[..max_size].copy_from_slice(&world[0][..max_size]);
+
+    for col in 1..max_size {
+        for row in 1..max_size {
+            if world[row][col] > sizes[col] {
+                visible[row][col] = true;
+                sizes[col] = world[row][col];
+            }
+        }
+    }
+}
+
+fn biggest_bottom(world: &World, max_size: usize, visible: &mut Visible) {
+    let mut sizes: [u8; 100] = [0; 100];
+
+    for i in 0..max_size {
+        sizes[i] = world[max_size - 1][i];
+    }
+
+    for col in 1..max_size {
+        for i in 1..max_size {
+            let row = max_size - i;
+            if world[row][col] > sizes[col] {
+                visible[row][col] = true;
+                sizes[col] = world[row][col];
+            }
+        }
+    }
+}

2022/src/days/mod.rs

@@ -5,3 +5,4 @@ pub mod day4;
 pub mod day5;
 pub mod day6;
 pub mod day7;
+pub mod day8;

2022/src/main.rs

@@ -33,6 +33,9 @@ fn run_day(number: i32) -> Result<()> {
         7 => {
             days::day7::run()?;
         }
+        8 => {
+            days::day8::run()?;
+        }
         _ => return Err(anyhow!("Invalid day provided")),
     }
     Ok(())
@@ -61,7 +64,7 @@ fn main() -> Result<()> {
                 };
                 println!("Day {}", number);
                 run_day(number)?;
-                println!("");
+                println!();
             }
         }
     }

2022/tests/day8.txt

@@ -0,0 +1,5 @@
+30373
+25512
+65332
+33549
+35390