From b931e0783dbedff50ddf18014c8aba7fd7f661a3 Mon Sep 17 00:00:00 2001
From: CyC2018 <zhengyc101@163.com>
Date: Sat, 31 Oct 2026 14:03:54 +0800
Subject: [PATCH] =?UTF-8?q?Update=20=E7=AE=97=E6=B3=95=20-=20=E6=8E=92?=
 =?UTF-8?q?=E5=BA=8F.md?=
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堆的删除补充空堆检查并注明容量，快速选择先打乱数组。
---
 notes/算法 - 排序.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/notes/算法 - 排序.md b/notes/算法 - 排序.md
index da0d046e..ed678c5a 100644
--- a/notes/算法 - 排序.md	
+++ b/notes/算法 - 排序.md	
@@ -363,6 +363,7 @@ public class ThreeWayQuickSort<T extends Comparable<T>> extends QuickSort<T> {
 
 ```java
 public T select(T[] nums, int k) {
+    shuffle(nums);
     int l = 0, h = nums.length - 1;
     while (h > l) {
         int j = partition(nums, l, h);
@@ -397,6 +398,7 @@ public class Heap<T extends Comparable<T>> {
     private T[] heap;
     private int N = 0;
 
+    // 容量固定为 maxN，插入超过 maxN 个元素时数组越界
     public Heap(int maxN) {
         this.heap = (T[]) new Comparable[maxN + 1];
     }
@@ -471,6 +473,8 @@ public void insert(T v) {
 
 ```java
 public T delMax() {
+    if (isEmpty())
+        throw new NoSuchElementException("堆为空");
     T max = heap[1];
     swap(1, N--);
     heap[N + 1] = null;