day 10 part 1

src/bin/day10.rs

@@ -132,11 +132,26 @@ fn main() -> anyhow::Result<()> {
 			}
 		}
 	}
+	// we can't do this so we filter the broken ones away
+	let start = start.unwrap();
+	for (row_diff, col_diff) in [NORTH, EAST, SOUTH, WEST] {
+		let other = match (
+			start.row.checked_add_signed(row_diff),
+			start.col.checked_add_signed(col_diff)
+		) {
+			(Some(row), Some(col)) if row < grid.len() && col < grid[start.row].len() => {
+				Node { row, col }
+			},
+			_ => continue
+		};
+		if !adj.0[&other].contains(&start) {
+			adj.0.get_mut(&start).unwrap().remove(&other);
+		}
+	}
 
-	// 6749 is too low
 	println!(
 		"{:?}",
-		adj.dij(start.unwrap())
+		adj.dij(start)
 			.into_iter()
 			.max_by_key(|(_, dist)| *dist)
 			.unwrap()