From 2c73258d0b73b1fcb53973ebf7cf2c351ae11c2f Mon Sep 17 00:00:00 2001
From: Ewan Mount <ejmount@users.noreply.github.com>
Date: Sat, 22 Oct 2022 19:52:48 +0100
Subject: [PATCH] Adding short-circuit if there's no children, to save a
 compare

---
 src/k_smallest.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/k_smallest.rs b/src/k_smallest.rs
index 8141792d3..ab7f19c86 100644
--- a/src/k_smallest.rs
+++ b/src/k_smallest.rs
@@ -152,6 +152,10 @@ where
         let (left_idx, right_idx) = children_of(origin);
         let (left_item, right_item) = (self.get(left_idx), self.get(right_idx));
 
+        if left_item.is_none() { // the left is the earlier child, so if it doesn't exist there's nothing to swap with
+            return;
+        }
+
         let cmp = self
             .compare(left_item, right_item)
             .unwrap_or(Ordering::Greater); // The right item may not exist, so default to picking the left, i.e. lower