排序算法总结

代码写久了，越发的觉得写到后来回归的都是基础。顿时觉得后悔大一大二没好好学这些计算机基础课程，亏大了。
总结下排序算法：

package 排序算法;/** * 1.选择排序  * 2.插入排序  * 3.归并排序  * 4.快速排序 *  * @author Administrator *  */public class 四种排序算法 {public static void main(String[] args) {int[] arr = { 2, 5, 6, 7, 4, 3, 1, 1, 3, 4, 5, 1, 3, 6, 3 };// selectSort(arr);// insertedSort(arr);// mergeSort(arr, 0, arr.length - 1);quickSort(arr, 0, arr.length - 1);out(arr);}// 输出public static void out(int[] arr) {for (int e : arr)System.out.print(e + ",");}// 1.选择排序public static void selectSort(int[] a) {for (int i = 0; i < a.length; i++)for (int j = i + 1; j < a.length; j++) {int key = a[i];if (key > a[j]) {a[i] = a[j];a[j] = key;}}}// 2.插入排序public static void insertedSort(int[] a) {for (int i = 1; i < a.length; i++) {int key = a[i];int j = i - 1;while (j >= 0 && key < a[j]) {a[j + 1] = a[j];a[j] = key;j--;}}}// 3.归并排序(分治法)public static void mergeSort(int[] a, int low, int high) {if (low < high) {int mid = (low + high) / 2;// 递归到最小原子mergeSort(a, low, mid);mergeSort(a, mid + 1, high);// 合并数组mergeArray(a, low, mid, high);}}// 合并数组private static void mergeArray(int[] a, int low, int mid, int high) {int N = high - low;int[] temp = new int[N + 1];int i = low, j = mid + 1;int m = mid, n = high;int k = 0;while (i <= m && j <= n)temp[k++] = (a[i] < a[j] ? a[i++] : a[j++]);while (i <= m)temp[k++] = a[i++];while (j <= n)temp[k++] = a[j++];for (i = 0; i < k; i++)a[low + i] = temp[i];}// 4.快速排序(分治法)public static void quickSort(int[] a, int low, int high) {if (low < high) {int r = adjustArray(a, low, high);quickSort(a, low, r - 1);quickSort(a, r + 1, high);}}// 提取数组中的首个元素，分割。小的元素放在<strong>标志</strong>的左边，比// 标志大的元素放在其右边，最后返回标志元素的位置private static int adjustArray(int[] a, int low, int high) {int i = low, j = high;int spcValue = a[low];while (i < j) {while (a[j] >= spcValue && i < j)j--;if (a[j] < spcValue)a[i++] = a[j];while (a[i] <= spcValue && i < j)i++;if (a[i] > spcValue)a[j--] = a[i];}a[i] = spcValue;return i;}}