Java：反向排序方法

Question

所以这些排序方法按照从小到大的顺序对数字进行排序，我该如何反转这些？我试过反转操作，但似乎不起作用：/

仍在努力学习Java，感谢您的帮助

//Selection Sort Method
public static void SelectionSort(int a[], int n) {
    int smallest;
    for (int i = 0; i < a.length - 1; i++) {
        smallest = i;
        //see if there is a smaller number further in the array
        for (int index = i + 1; index < a.length; index++) {
            if (a[index] < a[smallest]) {
                swap(a, smallest, index);
            }
        }
    }
}

//Selection Sort swap method to call on
public static void swap(int array2[], int first, int second) {
    int hold = array2[first];
    array2[first] = array2[second];
    array2[second] = hold;
}

//Bubble Sort Method
public static void BubbleSort(int a[], int n) {
    int i, j, t = 0;
    for (i = 0; i < n; i++) {
        for (j = 1; j < (n - i); j++) {
            if (a[j - 1] > a[j]) {
                t = a[j - 1];
                a[j - 1] = a[j];
                a[j] = t;
            }
        }
    }
}

//Insertion Sort Method
public static void InsertionSort(int a[], int n) {
    int insert;
    for (int next = 1; next < a.length; next++) {
        insert = a[next];
        int moveItem = next;
        while (moveItem > 0 && a[moveItem - 1] > insert) {
            a[moveItem] = a[moveItem - 1];
            moveItem--;
        }
        a[moveItem] = insert;
    }
}

//Quick Sort Method
public static void QuickSort(int a[], int low, int high) {
    int partitionLoc;
    if (low < high) {
        partitionLoc = partition(a, low, high);
        QuickSort(a, low, partitionLoc - 1);
        QuickSort(a, partitionLoc + 1, high);
    }
}

public static int partition(int a2[], int left, int right) {
    boolean moveLeft = true;
    int separator = a2[left];

    while (left < right) {
        if (moveLeft == true) {
            while ((a2[right] >= separator) && (left < right)) {
                right--;
            }
            a2[left] = a2[right];
            moveLeft = false;
        } else {
            while ((a2[left] <= separator) && (left < right)) {
                left++;
            }
            a2[right] = a2[left];
            moveLeft = true;
        }
    }
    a2[left] = separator;
    return left;
}

Answer 1

您可以保留您的方法并反转数组：

public static void reverse(int[] a) {
    for (int i = 0 ; i < a.length / 2 ; i++) {
        int t = a[i];
        a[i] = a[a.length - 1 - i];
        a[a.length - 1 - i] = t;
    }
}

int[] a = // ...
whateverSort(a);
reverse(a);

Answer 2

只需反转每个排序中的比较：

选择排序

a[index] < a[smallest] => a[index] > a[smallest]

冒泡排序
```
a[j - 1] > a[j] => a[j - 1] < a[j]
```

插入排序

a[moveItem - 1] > insert => a[moveItem - 1] < insert

快速排序

(a2[right] >= separator) => (a2[right] <= separator) 
(a2[left] <= separator) => (a2[left] >= separator)

Java：反向排序方法

Java: Reverse sorting methods

java

quicksort

bubble-sort

insertion-sort

selection-sort