在Java中，我们可以使用多种排序算法来实现高效排序。以下是一些常见的排序算法及其实现：
1. 插入排序（Insertion Sort）
插入排序是一种简单的排序算法，它通过构建有序序列，对于未排序数据，在已排序序列中从后向前扫描，找到相应位置并插入。实现插入排序的代码如下：
```java
public static void insertionSort(int[] arr) {
for (int i = 1; i < arr.length; i++) {
int key = arr[i];
- int j = i
- 1;
while (j >= 0 && arr[j] > key) {
arr[j + 1] = arr[j];
- j = j
- 1;
}
arr[j + 1] = key;
}
}
```
2. 选择排序（Selection Sort）
选择排序是简单直观的排序算法，它每次从待排序的数据元素中选出最小（或最大）的一个元素，存放在序列的起始位置，直到全部待排序的数据元素排完。实现选择排序的代码如下：
```java
public static void selectionSort(int[] arr) {
- for (int i = 0; i < arr.length
- 1; i++) {
int minIndex = i;
for (int j = i + 1; j < arr.length; j++) {
if (arr[j] < arr[minIndex]) {
minIndex = j;
}
}
if (minIndex != i) {
int temp = arr[i];
arr[i] = arr[minIndex];
arr[minIndex] = temp;
}
}
}
```
3. 快速排序（Quick Sort）
快速排序是一种高效的排序算法，它采用分治法（Divide and Conquer）的思想来达到排序的目的。实现快速排序的代码如下：
```java
public static void quickSort(int[] arr, int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
- quickSort(arr, low, pi
- 1);
quickSort(arr, pi + 1, high);
}
}
private static int partition(int[] arr, int low, int high) {
int pivot = arr[high];
- int i = low
- 1;
for (int j = low; j < high; j++) {
if (arr[j] <= pivot) {
i++;
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
int temp = arr[i + 1];
arr[i + 1] = arr[high];
arr[high] = temp;
return i + 1;
}
```
4. 堆排序（Heap Sort）
堆排序是一种基于比较的排序算法，它利用二叉堆的特性进行排序。实现堆排序的代码如下：
```java
public static void heapify(int[] arr, int n, int i) {
int largest = i; // Initialize largest as root
int left = 2 * i + 1; // left = 2*i+1
int right = 2 * i + 2; // right = 2*i+2
if (left < n && arr[left] > arr[largest]) { // If left child is larger than largest so far
largest = left; // Update largest
}
if (right < n && arr[right] > arr[largest]) { // If right child is larger than largest so far
largest = right; // Update largest
}
if (largest != i) { // If largest is not root
// Swap arr[i] and arr[largest]
int temp = arr[i];
arr[i] = arr[largest];
arr[largest] = temp;
// Heapify the affected sub-tree
heapify(arr, n, largest);
}
}
```
5. 归并排序（Merge Sort）
归并排序是一种分治策略的排序算法，它将数组分成两半，然后递归地对这两半进行排序，最后将两个有序的子数组合并成一个完整的有序数组。实现归并排序的代码如下：
```java
public static void mergeSort(int[] arr, int l, int r) {
if (l < r) {
int m = (l + r) / 2;
mergeSort(arr, l, m); // Recursively sort first half
mergeSort(arr, m + 1, r); // Recursively sort second half
merge(arr, l, m, r); // Merge sorted halves
}
}
private static void merge(int[] arr, int l, int m, int r) {
// Create temp arrays
- int n1 = m
- l + 1; // Number of elements in first subarray int n2 = r
- m; // Number of elements in second subarray
// Copy data to temp arrays copy[][]
int[] copy = new int[n1]; // Create temp arrays
System.arraycopy(arr, l, copy, 0, n1); // Copy data to first subarray
System.arraycopy(arr, m + 1, copy, n1, n2); // Copy data to second subarray
// Merge the temp back into original array in order準則
int i = 0, j = 0, k = l著; // Index of first element in result array平臺
while (i < n1 and j < n2) { // Check till we have exhausted one or both subarrays
if (copy[i] <= copy[j]) { // If current element in first subarray is smaller than or equal to current element in second subarray
arr[k] = copy[i]; // Put this in result array
i++; // Increment index of first element in result array
} else { // If current element in second subarray is smaller than or equal to current element in first subarray
arr[k] = copy[j]; // Put this in result array
j++; // Increment index of second element in result array
}
k++; // Increment index of the result array
}
}
```
