# 堆排序

• 使用陣列`ARR`的元素構建堆`H`
• 重復刪除階段`1`中形成的堆的根元素。

``````HEAP_SORT(ARR, N)

重複 i=0 到 N-1
CALL INSERT_HEAP(ARR, N, ARR[i])
[結束回圈]

當 N > 0 時，重複執行
CALL Delete_Heap(ARR,N,VAL)
SET N = N+1
[結束回圈]

``````

``````#include<stdio.h>
int temp;

void heapify(int arr[], int size, int i)
{
int largest = i;
int left = 2*i + 1;
int right = 2*i + 2;

if (left < size && arr[left] >arr[largest])
largest = left;

if (right < size && arr[right] > arr[largest])
largest = right;

if (largest != i)
{
temp = arr[i];
arr[i]= arr[largest];
arr[largest] = temp;
heapify(arr, size, largest);
}
}

void heapSort(int arr[], int size)
{
int i;
for (i = size / 2 - 1; i >= 0; i--)
heapify(arr, size, i);
for (i=size-1; i>=0; i--)
{
temp = arr[0];
arr[0]= arr[i];
arr[i] = temp;
heapify(arr, i, 0);
}
}

void main()
{
int arr[] = {1, 10, 2, 3, 4, 1, 2, 100,23, 2};
int i;
int size = sizeof(arr)/sizeof(arr[0]);

heapSort(arr, size);

printf("printing sorted elements\n");
for (i=0; i<size; ++i)
printf("%d\n",arr[i]);
}
``````

``````printing sorted elements

1
1
2
2
2
3
4
10
23
100
``````

``````using System;
public class HeapSorting {
static void heapify(int[] arr, int size, int i)
{
int largest = i;
int left = 2*i + 1;
int right = 2*i + 2;
int temp;
if (left < size && arr[left] > arr[largest])
largest = left;

if (right < size && arr[right] > arr[largest])
largest = right;

if (largest != i)
{
temp = arr[i];
arr[i]= arr[largest];
arr[largest] = temp;
heapify(arr, size, largest);
}
}

static void heapSort(int[] arr, int size)
{
int i;
int temp;
for (i = size / 2 - 1; i >= 0; i--)
heapify(arr, size, i);
for (i=size-1; i>=0; i--)
{
temp = arr[0];
arr[0]= arr[i];
arr[i] = temp;
heapify(arr, i, 0);
}
}

public void Main()
{
int[] arr = {1, 10, 2, 3, 4, 1, 2, 100, 23, 2};
int i;
heapSort(arr, 10);
Console.WriteLine("printing sorted elements");
for (i=0; i<10; ++i)
Console.WriteLine(arr[i]);
}
}
``````

``````printing sorted elements

1
1
2
2
2
3
4
10
23
100
``````