implement size_hint

day08/src/matrix/collumns.rs

@@ -55,6 +55,11 @@ impl<'a, T: Clone> Iterator for MatrixCollumn<'a, T> {
             None
         }
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let remaining = (self.parent.parent.height - self.index) as usize;
+        (remaining, Some(remaining))
+    }
 }
 
 impl<'a, T: Clone> ExactSizeIterator for MatrixCollumn<'a, T> {}