From adbaf7a9cdc3f67116e2034d0e5e235779dae286 Mon Sep 17 00:00:00 2001 From: Alexey Shmalko Date: Wed, 1 May 2019 23:26:06 +0300 Subject: [PATCH] BinaryHeap: add min-heap example --- src/liballoc/collections/binary_heap.rs | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/src/liballoc/collections/binary_heap.rs b/src/liballoc/collections/binary_heap.rs index 8c142a3d317c6..c355361b53c46 100644 --- a/src/liballoc/collections/binary_heap.rs +++ b/src/liballoc/collections/binary_heap.rs @@ -207,6 +207,30 @@ use super::SpecExtend; /// // The heap should now be empty. /// assert!(heap.is_empty()) /// ``` +/// +/// ## Min-heap +/// +/// Either `std::cmp::Reverse` or a custom `Ord` implementation can be used to +/// make `BinaryHeap` a min-heap. This makes `heap.pop()` return the smallest +/// value instead of the greatest one. +/// +/// ``` +/// use std::collections::BinaryHeap; +/// use std::cmp::Reverse; +/// +/// let mut heap = BinaryHeap::new(); +/// +/// // Wrap values in `Reverse` +/// heap.push(Reverse(1)); +/// heap.push(Reverse(5)); +/// heap.push(Reverse(2)); +/// +/// // If we pop these scores now, they should come back in the reverse order. +/// assert_eq!(heap.pop(), Some(Reverse(1))); +/// assert_eq!(heap.pop(), Some(Reverse(2))); +/// assert_eq!(heap.pop(), Some(Reverse(5))); +/// assert_eq!(heap.pop(), None); +/// ``` #[stable(feature = "rust1", since = "1.0.0")] pub struct BinaryHeap { data: Vec,