day08: Adapt code for part 2

I could probably optimize that by getting the iterators for all 4
directions and then to the scan on each of them in a loop, but I'm with
with this right now.

day08/src/main.rs

@@ -19,29 +19,57 @@ fn main() -> Result<(), Box<dyn error::Error>> {
 	let width = width;
 	let height = map.len() / width;
 
-	let mut visible_count = 0;
+	let mut scenic_scores = vec![];
 	for i in 0..map.len() {
 		let line = i / height;
 		let column = i % width + 1; // we need + 1 here, because there is no modulo 0
+		let mut scenic_score = 1;
+
+		// tree-houses cannot be built on the outside, so we have to skip those outside-trees for
+		// the calculation
+		if line == 0 || line == height - 1 || column == 1 || column == width {
+			continue;
+		}
 
 		// println!("line: {}, column: {}, self: {}", line, column, map[i]);
-		let left = map[(line * width)..i].iter().max();
+		let left = map[(line * width)..i].iter()
+			.rev()
+			.scan(true, |state, &x| if !*state { None } else { if x >= map[i] { *state = false }; Some(1) })
+			// .inspect(|x| println!("{x}"))
+			.count();
+		if left > 0 {
+			scenic_score *= left;
+		}
 		let right = map[i..((line + 1) * width)].iter()
 			.enumerate()
 			.filter_map(|(j, x)| if (j + i) / height == line && j > 0 { Some(x) } else { None })
-			.max();
+			.scan(true, |state, &x| if !*state { None } else { if x >= map[i] { *state = false }; Some(1) })
+			.count();
+		if right > 0 {
+			scenic_score *= right;
+		}
 		// let right = map[(i + 1)..((line + 1) * width)].iter().max();
 		let up = map[0..i].iter()
 			.enumerate()
 			//.inspect(|(j, x)| println!("{j} {x}"))
 			.filter_map(|(j, x)| if (j + 1) % width == column { Some(x) } else { None })
-			.max();
+			.rev()
+			.scan(true, |state, &x| if !*state { None } else { if x >= map[i] { *state = false }; Some(1) })
+			.count();
+		if up > 0 {
+			scenic_score *= up;
+		}
 		let down = map[i..].iter()
 			.enumerate()
 			.filter_map(|(j, x)| if (i + j + 1) % width == column && j > 0 { Some(x) } else { None })
-			.max();
+			.scan(true, |state, &x| if !*state { None } else { if x >= map[i] { *state = false }; Some(1) })
+			.count();
+		if down > 0 {
+			scenic_score *= down;
+		}
 		// println!("left: {:?}, right: {:?}, up: {:?}, down: {:?}", &left, &right, &up, &down);
 
+		/*
 		for direction_max in vec![left, right, up, down] {
 			match direction_max {
 				Some(x) if x < &map[i] => {
@@ -55,9 +83,10 @@ fn main() -> Result<(), Box<dyn error::Error>> {
 				_ => ()
 			}
 		}
-		// println!("visible: {visible_count}");
+		*/
+		scenic_scores.push(scenic_score);
 	}
 
-    println!("Found {visible_count} visible trees.");
+    println!("Highest scenic score is {}", scenic_scores.iter().max().unwrap_or(&0));
     Ok(())
 }