[冒泡排序算法]、[选择排序算法]
1 /**
2 * @Description:<p>冒泡排序算法实现</p>
3 * @time:2016/03/29 下午14:40
4 */
5 public static void bubbleSort(int[] arr) {
6
7 if (arr == null || arr.Length == 0)
8 return;
9 for (int i = 0; i < arr.Length - 1; i++) {
10 for (int j = arr.Length - 1; j >i; j--)
11 {
12 if (arr[j] < arr[j - 1]) {
13 swap(arr, j - 1, j);
14 }
15 }
16 }
17 }
18
19 public static void swap(int[] arr, int i, int j) {
20 int temp = arr[i];
21 arr[i] = arr[j];
22 arr[j] = temp;
23 }
1 /*
2 * @Description:<p>选择排序算法实现</p>
3 * @time:2016/03/29 下午14:42
4 */
5
6 public static void selectSort(int[] arr) {
7 if (arr == null || arr.Length == 0)
8 return;
9 int minIndex = 0;
10 for (int i = 0; i < arr.Length - 1; i++) { //只需要比较n-1次
11 minIndex = i;
12 for (int j = i + 1; j < arr.Length; j++) { //从i+1开始比较，因为minIndex默认为i了,i就没必要比了。
13 if (arr[j] < arr[minIndex]) {
14 minIndex = j;
15 }
16 }
17 if (minIndex != i) { //如果minIndex不为i,说明找到了更小的值，交换之。
18 swap(arr, i, minIndex);
19
20 }
21 }
22
23 }
24
25 public static void swap(int[] arr, int i, int j) {
26 int temp = arr[i];
27 arr[i] = arr[j];
28 arr[j] = temp;
29 }
插入排序算法
1 public static void insertSort(int[] arr) {
2 if (arr == null || arr.Length == 0)
3 return;
4 for (int i = 1; i < arr.Length; i++) {//假设第一个数位置正确的；要往后移，必须要假设第一个
5 int j = i;
6 int target = arr[i]; //待插入的
7
8 //后移
9 while (j > 0 && target < arr[j - 1]) {
10 arr[j] = arr[j - 1];
11 j--;
12 }
13 //插入
14 arr[j] = target;
15 }
16 }
快速排序算法
1 //一次划分
2 public static int partition(int[] arr, int left, int right)
3 {
4 int pivotKey = arr[left];
5 int pivotPointer = left;
6
7 while (left < right)
8 {
9 while (left < right && arr[right] >= pivotKey)
10 right--;
11 while (left < right && arr[left] <= pivotKey)
12 left++;
13 swap(arr, left, right); //把大的交换到右边，把小的交换到左边。
14 }
15 swap(arr, pivotPointer, left); //最后把pivot交换到中间
16 return left;
17
18 }
19
20 public static void quickSort(int[] arr, int left, int right)
21 {
22 if (left >= right)
23 return;
24 int pivotPos = partition(arr, left, right);
25 quickSort(arr, left, pivotPos - 1);
26 quickSort(arr, pivotPos + 1, right);
27 }
28
29 public static void sort(int[] arr)
30 {
31 if (arr == null || arr.Length == 0)
32 return;
33 quickSort(arr, 0, arr.Length - 1);
34 }
35
36 public static void swap(int[] arr, int left, int right)
37 {
38 int temp = arr[left];
39 arr[left] = arr[right];
40 arr[right] = temp;
41 }
42
43 ====================================优化以上代码
44 public static int partition(int[] arr, int left, int right)
45 {
46 int pivotKey = arr[left];
47 while (left < right)
48 {
49 while (left < right && arr[right] >= pivotKey)
50 right--;
51 arr[left] = arr[right]; //把小的移动到左边
52 while (left < right && arr[left] <= pivotKey)
53 left++;
54 arr[right] = arr[left];//把大的移动到右边
55 }
56 arr[left] = pivotKey; //最后把pivot赋值到中间
57 return left;
58
59 }
60
61 public static void quickSort(int[] arr, int left, int right)
62 {
63 if (left >= right)
64 return;
65 int pivotPos = partition(arr, left, right);
66 quickSort(arr, left, pivotPos - 1);
67 quickSort(arr, pivotPos + 1, right);
68 }
69 public static void sort(int[] arr)
70 {
71 if (arr == null || arr.Length == 0)
72 return;
73 quickSort(arr, 0, arr.Length - 1);
74 }
希尔排序
1 static void Main(string[] args)
2 {
3 int[] arr={1,22,32,13,35,42,48,55};
4 shellSort(arr);
5 for (int i = 0; i < arr.Length; i++)
6 {
7 Console.Write("{0},", arr[i]);
8 }
9 Console.ReadLine();
10 }
11
12 public static void shellInsert(int[] arr, int d) {
13 for (int i = d; i < arr.Length; i++) {
14 int j = i - d;
15 int temp = arr[i]; //记录要插入的数据
16 while (j >= 0 && arr[j] > temp) { //从后向前，找到比其小的数的位置
17 arr[j + d] = arr[j]; //向后挪动
18 j -= d;
19 }
20
21 if (j != i - d) //存在比其小的数
22 arr[j + d] = temp;
23
24 }
25 }
26 public static void shellSort(int[] arr) {
27 if (arr == null || arr.Length == 0)
28 return;
29 int d = arr.Length / 2;
30 while (d >= 1) {
31 shellInsert(arr, d);
32 d /= 2;
33 }
34 }
归并排序
1 static void Main(string[] args)
2 {
3 int[] arr={1,22,32,13,35,42,48,55};
4 mergeSort(arr);
5 for (int i = 0; i < arr.Length; i++)
6 {
7 Console.Write("{0},", arr[i]);
8 }
9 Console.ReadLine();
10 }
11
12 public static void mergeSort(int[] arr) {
13 mSort(arr, 0, arr.Length - 1);
14 }
15
16 public static void mSort(int[] arr, int left, int right) {
17 if (left >= right)
18 return;
19 int mid = (left + right) / 2;
20
21 mSort(arr, left, mid);
22 mSort(arr, mid + 1, right);
23 merge(arr, left, mid, right);
24 }
25
26 public static void merge(int[] arr, int left, int mid, int right) {
27 //[left,mid][mid+1,right]
28 int[] temp = new int[right - left + 1];
29
30 int i = left;
31 int j = mid + 1;
32 int k = 0;
33 while (i <= mid && j <= right) {
34 if (arr[i] <= arr[j])
35 {
36 temp[k++] = arr[i++];
37 }
38 else {
39 temp[k++] = arr[j++];
40 }
41 }
42
43 while (i <= mid) {
44 temp[k++] = arr[i++];
45 }
46
47 while (j <= right) {
48 temp[k++] = arr[j++];
49 }
50
51 for (int p = 0; p < temp.Length; p++) {
52 arr[left + p] = temp[p];
53 }
54
55 }
时间： 2024-10-23 12:29:42