Auto merge of #122945 - andy-k:sorted-vec-example, r=jhpratt

improve example on inserting to a sorted vector to avoid shifting equal elements

1 files changed, 4 insertions, 2 deletions

diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index 5ff7f184a6d..e2fc320f280 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -2464,8 +2464,10 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// let mut deque: VecDeque<_> = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55].into();
     /// let num = 42;
-    /// let idx = deque.partition_point(|&x| x < num);
-    /// // The above is equivalent to `let idx = deque.binary_search(&num).unwrap_or_else(|x| x);`
+    /// let idx = deque.partition_point(|&x| x <= num);
+    /// // If `num` is unique, `s.partition_point(|&x| x < num)` (with `<`) is equivalent to
+    /// // `s.binary_search(&num).unwrap_or_else(|x| x)`, but using `<=` may allow `insert`
+    /// // to shift less elements.
     /// deque.insert(idx, num);
     /// assert_eq!(deque, &[0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
     /// ```