fix day9 overflow

src/day9.rs

@@ -44,11 +44,13 @@ impl Preamble {
     fn find_sum_pair(&self, total: usize) -> Option<(usize, usize)> {
         for idx in 0..25 {
             let entry = self.entries[(self.entries_start_idx + idx) % 25];
+            if entry <= total {
                 let needed = total - entry;
                 if self.set.contains(&needed) {
                     return Some((entry, needed));
                 }
             }
+        }
         None
     }
 }