part 2 done; just did it the hard way

08/main.rs

@@ -5,8 +5,8 @@ use std::io::BufRead;
 use std::path::Path;
 use std::time::Instant;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
-struct Tree(i8, bool);
+struct Tree(i8, bool); // height, visible from outside
 
 fn main() {
     let now = Instant::now();
@@ -85,4 +85,63 @@ fn part_one() {
     println!("{}", total);
 }
 
-fn part_two() {}
+fn part_two() {
+    let mut grid: Vec<Vec<Tree>> = vec![];
+    let mut best = 0;
+    if let Ok(lines) = read_lines("./inputs/input") {
+        for (i, line) in lines.enumerate() {
+            if let Ok(row) = line {
+                grid.push(vec![]);
+                for c in row.chars() {
+                    grid[i].push(Tree((c as i8) - 48, false));
+                }
+            }
+        }
+    }
+    // alright, we'll do this the hard way
+    // we can skip the edges, because they all multiply by 0 in one way or another
+    for i in 1..grid.len() - 1 {
+        for j in 1..grid.len() - 1 {
+            let (mut score, mut acc) = (1, 0); // a base score and the counter we'll reuse
+            for x in (0..j).rev() {
+                // left
+                acc += 1;
+                if grid[i][x].0 >= grid[i][j].0 {
+                    break;
+                }
+            }
+            score *= acc;
+            acc = 0;
+            for x in (0..i).rev() {
+                // up
+                acc += 1;
+                if grid[x][j].0 >= grid[i][j].0 {
+                    break;
+                }
+            }
+            score *= acc;
+            acc = 0;
+            for x in (j + 1)..grid.len() {
+                // right
+                acc += 1;
+                if grid[i][x].0 >= grid[i][j].0 {
+                    break;
+                }
+            }
+            score *= acc;
+            acc = 0;
+            for x in (i + 1)..grid.len() {
+                // down
+                acc += 1;
+                if grid[x][j].0 >= grid[i][j].0 {
+                    break;
+                }
+            }
+            score *= acc;
+            if score > best {
+                best = score;
+            }
+        }
+    }
+    println!("{}", best);
+}