Java三路归并排序
时间: 2023-11-15 16:01:59 浏览: 47
Java三路归并排序是一种基于归并排序的算法,它将待排序数组分成三个部分,然后递归地将每个部分排序,最后将它们合并成一个有序数组。与传统的二路归并排序不同,三路归并排序将数组分成三个部分,这样可以减少比较和交换的次数,从而提高排序效率。Java三路归并排序的时间复杂度为O(nlogn),空间复杂度为O(n)。它是一种稳定的排序算法,适用于大规模数据的排序。
相关问题
三路归并排序Java代码
以下是三路归并排序的Java代码:
```
public class MergeSort {
public static void mergeSort(int[] arr, int left, int right) {
if (left >= right) {
return;
}
int mid1 = left + (right - left) / 3;
int mid2 = left + 2 * (right - left) / 3;
mergeSort(arr, left, mid1);
mergeSort(arr, mid1 + 1, mid2);
mergeSort(arr, mid2 + 1, right);
merge(arr, left, mid1, mid2, right);
}
public static void merge(int[] arr, int left, int mid1, int mid2, int right) {
int[] temp = new int[right - left + 1];
int i = left, j = mid1 + 1, k = mid2 + 1, index = 0;
while (i <= mid1 && j <= mid2 && k <= right) {
if (arr[i] <= arr[j] && arr[i] <= arr[k]) {
temp[index++] = arr[i++];
} else if (arr[j] <= arr[i] && arr[j] <= arr[k]) {
temp[index++] = arr[j++];
} else {
temp[index++] = arr[k++];
}
}
while (i <= mid1 && j <= mid2) {
if (arr[i] <= arr[j]) {
temp[index++] = arr[i++];
} else {
temp[index++] = arr[j++];
}
}
while (i <= mid1 && k <= right) {
if (arr[i] <= arr[k]) {
temp[index++] = arr[i++];
} else {
temp[index++] = arr[k++];
}
}
while (j <= mid2 && k <= right) {
if (arr[j] <= arr[k]) {
temp[index++] = arr[j++];
} else {
temp[index++] = arr[k++];
}
}
while (i <= mid1) {
temp[index++] = arr[i++];
}
while (j <= mid2) {
temp[index++] = arr[j++];
}
while (k <= right) {
temp[index++] = arr[k++];
}
for (int m = 0; m < temp.length; m++) {
arr[left + m] = temp[m];
}
}
}
```
java 实现二路归并排序
Java 实现二路归并排序的代码可以参考以下示例:
```java
public class MergeSort {
public static void mergeSort(int[] arr, int left, int right) {
if (left < right) {
int mid = left + (right - left) / 2;
mergeSort(arr, left, mid);
mergeSort(arr, mid + 1, right);
merge(arr, left, mid, right);
}
}
private static void merge(int[] arr, int left, int mid, int right) {
int[] temp = new int[right - left + 1];
int i = left, j = mid + 1, k = 0;
while (i <= mid && j <= right) {
if (arr[i] <= arr[j]) {
temp[k++] = arr[i++];
} else {
temp[k++] = arr[j++];
}
}
while (i <= mid) {
temp[k++] = arr[i++];
}
while (j <= right) {
temp[k++] = arr[j++];
}
for (int p = 0; p < temp.length; p++) {
arr[left + p] = temp[p];
}
}
public static void main(String[] args) {
int[] arr = {38, 27, 43, 3, 9, 82, 10};
mergeSort(arr, 0, arr.length - 1);
System.out.println(Arrays.toString(arr));
}
}
```
该代码实现了二路归并排序,时间复杂度为 O(nlogn)。