冒泡排序，选择排序，快速排序，堆排序与二分查找算法

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public class Test {public static void main(String[] args) {int arr[] = { 5, 2, 3, 1, 4, -4, 6, 2 };// arr = sort1(arr);// arr = sort2(arr);//arr = sort3(arr, 0, arr.length - 1);arr = sort4(arr);for (int i = 0; i < arr.length; i++) {System.out.println(arr[i]);}System.out.println("下标是:" + binarySearch(arr, 1));}// 冒泡排序public static int[] sort1(int[] arr) {for (int i = 0; i < arr.length - 1; i++) {for (int j = 0; j < arr.length - i - 1; j++) {if (arr[j] > arr[j + 1]) {int temp = arr[j];arr[j] = arr[j + 1];arr[j + 1] = temp;}}}return arr;}// 选择排序public static int[] sort2(int[] arr) {for (int i = 0; i < arr.length; i++) {int min = i;for (int j = i + 1; j < arr.length; j++) {if (arr[min] > arr[j]) {min = j;}}if (i != min) {int temp = arr[min];arr[min] = arr[i];arr[i] = temp;}}return arr;}// 快速排序public static int[] sort3(int arr[], int l, int r) {if (l < r) {int i = l, j = r, x = arr[l];while (i < j) {while (i < j && arr[j] >= x) {// 从向左找出第一个小于x的数并交换j--;}if (i < j) {arr[i++] = arr[j];}while (i < j && arr[i] < x) {i++;}if (i < j) {arr[j--] = arr[i];}}arr[i] = x;sort3(arr, l, i - 1);sort3(arr, i + 1, r);}return arr;}// 堆排序//3.交换public static void swap(int i, int j, int[] arr) { int temp = arr[i];arr[i] = arr[j];arr[j] = temp;}//2.排序public static int[] sort4(int arr[]) {for (int i = 0; i < arr.length - 1; i++) {buildMaxHeap(arr, arr.length - i - 1);swap(0, arr.length - i - 1, arr);}return arr;}//1.构建最大堆public static void buildMaxHeap(int[] array, int lastIndex) {for (int i = (lastIndex - 1) / 2; i >= 0; i--) {// 记录当前的节点int k = i;// 说明有左孩子while (2 * k + 1 <= lastIndex) {int bigIndex = 2 * k + 1;// 说明有右孩子if (bigIndex < lastIndex) {if (array[bigIndex] < array[bigIndex + 1]) {bigIndex++;}}if (array[bigIndex] > array[i]) {swap(k, bigIndex, array);k = bigIndex;} else {break;}}}}// 二分查找public static int binarySearch(int arr[], int v) {int l = 0;int r = arr.length - 1;while (l < r) {int m = (l + r) / 2;if (arr[m] == v) {return m;} else if (arr[m] < v) {l = m + 1;} else if (arr[m] > v) {r = m - 1;}}return -1;}}
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