From f2a361f9cd461a14966fd6736f9ee964f3c29432 Mon Sep 17 00:00:00 2001
From: jerry <1310689026@qq.com>
Date: Wed, 30 Dec 2020 13:38:07 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A4=A7=E6=A0=B9=E5=A0=86?=
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---
 homework/heap/HeapSort.java | 75 +++++++++++++++++++++++++++++++++++++
 homework/heap/Main.java     | 20 ++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 homework/heap/HeapSort.java
 create mode 100644 homework/heap/Main.java

diff --git a/homework/heap/HeapSort.java b/homework/heap/HeapSort.java
new file mode 100644
index 0000000..e95eb09
--- /dev/null
+++ b/homework/heap/HeapSort.java
@@ -0,0 +1,75 @@
+package heap;
+
+public class HeapSort {
+    //构建大根堆：将array看成完全二叉树的顺序存储结构
+    public int[] buildMaxHeap(int[] array){
+        //从最后一个节点array.length-1的父节点（array.length-1-1）/2开始，直到根节点0，反复调整堆
+        for(int i=(array.length-2)/2;i>=0;i--){
+            adjustDownToUp(array, i,array.length);
+        }
+        return array;
+    }
+
+    //将元素array[k]自下往上逐步调整树形结构
+    public void adjustDownToUp(int[] array,int k,int length){
+        int temp = array[k];
+        for(int i=2*k+1; i<length-1; i=2*i+1){    //i为初始化为节点k的左孩子，沿节点较大的子节点向下调整
+            if(i<length && array[i]<array[i+1]){  //取节点较大的子节点的下标
+                i++;   //如果节点的右孩子>左孩子，则取右孩子节点的下标
+            }
+            if(temp>=array[i]){  //根节点 >=左右子女中关键字较大者，调整结束
+                break;
+            }else{   //根节点 <左右子女中关键字较大者
+                array[k] = array[i];  //将左右子结点中较大值array[i]调整到双亲节点上
+                k = i; //【关键】修改k值，以便继续向下调整
+            }
+        }
+        array[k] = temp;  //被调整的结点的值放人最终位置
+    }
+    
+  //堆排序
+    public int[] heapSort(int[] array){
+        array = buildMaxHeap(array); //初始建堆，array[0]为第一趟值最大的元素
+        for(int i=array.length-1;i>1;i--){
+            int temp = array[0];  //将堆顶元素和堆低元素交换，即得到当前最大元素正确的排序位置
+            array[0] = array[i];
+            array[i] = temp;
+            adjustDownToUp(array, 0,i);  //整理，将剩余的元素整理成堆
+        }
+        return array;
+    }
+    
+  //删除堆顶元素操作
+    public int[] deleteMax(int[] array){
+        //将堆的最后一个元素与堆顶元素交换，堆底元素值设为-99999
+        array[0] = array[array.length-1];
+        array[array.length-1] = -99999;
+        //对此时的根节点进行向下调整
+        adjustDownToUp(array, 0, array.length);
+        return array;
+    }
+    
+  //插入操作:向大根堆array中插入数据data
+    public int[] insertData(int[] array, int data){
+        array[array.length-1] = data; //将新节点放在堆的末端
+        int k = array.length-1;  //需要调整的节点
+        int parent = (k-1)/2;    //双亲节点
+        while(parent >=0 && data>array[parent]){
+            array[k] = array[parent];  //双亲节点下调
+            k = parent;
+            if(parent != 0){
+                parent = (parent-1)/2;  //继续向上比较
+            }else{  //根节点已调整完毕，跳出循环
+                break;
+            }
+        }
+        array[k] = data;  //将插入的结点放到正确的位置
+        return array;
+    }
+
+    public void toString(int[] array){
+        for(int i:array){
+            System.out.print(i+" ");
+        }
+    }
+}
diff --git a/homework/heap/Main.java b/homework/heap/Main.java
new file mode 100644
index 0000000..33ee98d
--- /dev/null
+++ b/homework/heap/Main.java
@@ -0,0 +1,20 @@
+package heap;
+
+public class Main {    
+    public static void main(String[] args) {
+        HeapSort hs = new HeapSort();
+        int[] array = {87,45,78,32,17,65,53,9,122};
+        System.out.println("构建大根堆：");
+        hs.toString(hs.buildMaxHeap(array));
+        System.out.println();
+        System.out.println("删除堆顶元素：");
+        hs.toString(hs.deleteMax(array));
+        System.out.println();
+        System.out.println("插入元素63:");
+        hs.toString(hs.insertData(array, 63));
+        System.out.println();
+        System.out.println("大根堆排序：");
+        hs.toString(hs.heapSort(array));
+    }
+
+}
-- 
Gitee