怎样实现java数组的稳定排序 - 问答

在 Java 中，稳定排序是指相等的元素在排序后保持原有的相对顺序。Java 提供了稳定的排序算法，如冒泡排序、插入排序和归并排序。以下是这些排序算法的实现：

冒泡排序（Bubble Sort）：

public class BubbleSort {
    public static void main(String[] args) {
        int[] arr = {64, 34, 25, 12, 22, 11, 90};
        bubbleSort(arr);
        System.out.println("Sorted array is:");
        printArray(arr);
    }

    public static void bubbleSort(int[] arr) {
        int n = arr.length;
        for (int i = 0; i < n - 1; i++) {
            for (int j = 0; j < n - i - 1; j++) {
                if (arr[j] > arr[j + 1]) {
                    // swap arr[j+1] 和 arr[j]
                    int temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
        }
    }

    public static void printArray(int[] arr) {
        for (int value : arr) {
            System.out.print(value + " ");
        }
    }
}

插入排序（Insertion Sort）：

public class InsertionSort {
    public static void main(String[] args) {
        int[] arr = {64, 34, 25, 12, 22, 11, 90};
        insertionSort(arr);
        System.out.println("Sorted array is:");
        printArray(arr);
    }

    public static void insertionSort(int[] arr) {
        int n = arr.length;
        for (int i = 1; i < n; ++i) {
            int key = arr[i];
            int j = i - 1;

            // Move elements of arr[0..i-1], that are greater than key, to one position ahead of their current position
            while (j >= 0 && arr[j] > key) {
                arr[j + 1] = arr[j];
                j = j - 1;
            }
            arr[j + 1] = key;
        }
    }

    public static void printArray(int[] arr) {
        for (int value : arr) {
            System.out.print(value + " ");
        }
    }
}

归并排序（Merge Sort）：

public class MergeSort {
    public static void main(String[] args) {
        int[] arr = {64, 34, 25, 12, 22, 11, 90};
        mergeSort(arr, 0, arr.length - 1);
        System.out.println("Sorted array is:");
        printArray(arr);
    }

    public static void mergeSort(int[] arr, int left, int right) {
        if (left < right) {
            int middle = (left + right) / 2;

            // Sort first and second halves
            mergeSort(arr, left, middle);
            mergeSort(arr, middle + 1, right);

            merge(arr, left, middle, right);
        }
    }

    public static void merge(int[] arr, int left, int middle, int right) {
        int n1 = middle - left + 1;
        int n2 = right - middle;

        // Create temp arrays
        int[] leftArray = new int[n1];
        int[] rightArray = new int[n2];

        // Copy data to temp arrays
        for (int i = 0; i < n1; ++i)
            leftArray[i] = arr[left + i];
        for (int j = 0; j < n2; ++j)
            rightArray[j] = arr[middle + 1 + j];

        // Merge the temp arrays
        int i = 0, j = 0;
        int k = left;
        while (i < n1 && j < n2) {
            if (leftArray[i] <= rightArray[j]) {
                arr[k] = leftArray[i];
                i++;
            } else {
                arr[k] = rightArray[j];
                j++;
            }
            k++;
        }

        // Copy the remaining elements of leftArray
        while (i < n1) {
            arr[k] = leftArray[i];
            i++;
            k++;
        }

        // Copy the remaining elements of rightArray
        while (j < n2) {
            arr[k] = rightArray[j];
            j++;
            k++;
        }
    }

    public static void printArray(int[] arr) {
        for (int value : arr) {
            System.out.print(value + " ");
        }
    }
}

这些排序算法都是稳定的，你可以根据需要选择合适的算法。

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