From 4caf6e5d3215104aadbf59f86eb96ea1b6a722a9 Mon Sep 17 00:00:00 2001
From: "gongruihan.1" <gongruihan.1@jd.com>
Date: Mon, 27 Apr 2026 16:14:35 +0800
Subject: [PATCH] fix: off-by-one bounds check in heap_sort::sink

  Change j < n to j + 1 < n to prevent out-of-bounds access
  on arr[j + 1] when j == n - 1.

  Fixes #3
---
 algorithmica/src/sort/heap_sort.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/algorithmica/src/sort/heap_sort.rs b/algorithmica/src/sort/heap_sort.rs
index f7a0483..6433a85 100644
--- a/algorithmica/src/sort/heap_sort.rs
+++ b/algorithmica/src/sort/heap_sort.rs
@@ -39,7 +39,7 @@ pub fn sink<T: Ord, F: Fn(&T, &T) -> bool>(arr: &mut [T], k: usize, n: usize, p:
     let mut k = k;
     while 2 * k < n {
         let mut j = 2 * k + 1;
-        if j < n && p(&arr[j], &arr[j + 1]) {
+        if j + 1 < n && p(&arr[j], &arr[j + 1]) {
             j += 1;
         }
         if !p(&arr[j], &arr[k]) {