快速排序、归并排序、堆排序

 1 void quick_sort(int q[], int l, int r)
 2 {
 3     if (l >= r) return;
 4 
 5     int i = l - 1, j = r + 1, x = q[l + r >> 1];
 6     while (i < j)
 7     {
 8         do i ++ ; while (q[i] < x);
 9         do j -- ; while (q[j] > x);
10         if (i < j) swap(q[i], q[j]);
11     }
12     quick_sort(q, l, j), quick_sort(q, j + 1, r);
13 }

 1 void merge_sort(int q[], int l, int r)
 2 {
 3     if (l >= r) return;
 4 
 5     int mid = l + r >> 1;
 6     merge_sort(q, l, mid);
 7     merge_sort(q, mid + 1, r);
 8 
 9     int k = 0, i = l, j = mid + 1;
10     while (i <= mid && j <= r)
11         if (q[i] < q[j]) tmp[k ++ ] = q[i ++ ];
12         else tmp[k ++ ] = q[j ++ ];
13 
14     while (i <= mid) tmp[k ++ ] = q[i ++ ];
15     while (j <= r) tmp[k ++ ] = q[j ++ ];
16 
17     for (i = l, j = 0; i <= r; i ++, j ++ ) q[i] = tmp[j];
18 }

 1 #include<iostream>
 2 using namespace std;
 3 
 4 void heapInsert(int arr[], int index)//添加一个元素，形成大根堆
 5 {
 6     while (arr[index] > arr[(index - 1) / 2])
 7     {
 8         swap(arr[index], arr[(index - 1) / 2]);
 9         index = (index - 1) / 2;
10     }
11 }
12 
13 void heapify(int arr[], int index, int heapSize)//改变一个元素，形成大根堆
14 {
15     int left = index * 2 + 1;
16     while (left < heapSize)
17     {
18         int largest = left + 1 < heapSize && arr[left + 1] > arr[left] ? left + 1 : left;
19 
20         largest = arr[largest] > arr[index] ? largest : index;
21         if (largest == index)
22         {
23             break;
24         }
25         else
26         {
27             swap(arr[largest], arr[index]);
28             index = largest;
29             left = index * 2 + 1;
30         }
31     }
32 }
33 
34 void heapSort(int arr[],int n)
35 {
36     if (n < 2)
37     {
38         return;
39     }
40 
41     //1、整体变成大根堆
42     for (int i = 0; i < n; i++)
43     {
44         heapInsert(arr, i);
45     }
46 
47     //2、最后一个位置与堆顶位置作交换
48     swap( arr[0], arr[--n]);
49     
50     while (n > 0)
51     {
52         heapify(arr, 0, n);//3、重新整理成大根堆
53         swap( arr[0], arr[--n]);//4、最后一个位置与堆顶位置作交换
54     }
55 }
56 
57 
58 int main()
59 {
60     int num[] = {9,5,4,2,3,1,8};
61     heapSort(num,7);
62     for(int i = 0;i < 7;++i)
63     {
64         cout << num[i] << endl;
65     }
66     return 0;
67 }