[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 }