java - 降序排序算法

Question

import javax.swing.*;

import java.lang.reflect.Array;
import java.util.Collections;
import java.util.Random;
import java.util.Scanner;

public class RandExample {

    public static void main(String[] args) {

            int MethodChoice = Integer.parseInt(JOptionPane.showInputDialog("What method would you like to use to sort the random numbers" + "\n" + "1 - Selection Sort" + "\n" + "2 - Bubble Sort" + "\n" + "3 - Insertion Sort" + "\n" + "4 - Quick Sort"));

            if (MethodChoice == 1) {

                    int iTotalCount = Integer.parseInt(JOptionPane.showInputDialog("What is the total number of integers?"));

                    int SortOrder = Integer.parseInt(JOptionPane.showInputDialog("1 - Ascending  "
                            + "2 - Descending"));

                    if (SortOrder == 2) {
                         int[] array = new int[iTotalCount];

                        System.out.println("After sorting using the Selection Sort, " + "Using Descending Order" + "the array is: ");

                        for(int count = array.length-1; count >= 0; count--)
                             System.out.print(array[count] + " ");

                        selectionSortReverse(array);

                    }

                    int[] array = new int[iTotalCount];

                    Random randomGenerator = new Random();

                    for (int i = 0; i < iTotalCount; i++) {
                       array[i] = randomGenerator.nextInt(1001);
                       System.out.print(" " + array[i]);
                    }

                    System.out.println("\n---------------------------------");
                    selectionSort(array);

                    //print out sorted list
                    System.out.println("After sorting using the Selection Sort," + " the array is:");
                    for (int count = 0; count < array.length; count++) {
                         System.out.print(array[count] + " ");
                    }
    }

我有一个调用selectionSortReverse(array)的子例程；当用户选择 2 使其按降序排序时，但当我点击 2 并继续时，它会按升序发布数字。我把它放在错误的地方了吗？这是我的选择排序反向子例程:

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

使用 cricket_007 的建议更新了代码

import javax.swing.*;

import java.lang.reflect.Array;
import java.util.Collections;
import java.util.Random;
public class RandExample {

private static int[] generateRandomArray(int size, int randomMax) {
    int[] array = new int[size];
    Random randomGenerator = new Random();
    for (int i = 0; i < size; i++) {
        array[i] = randomGenerator.nextInt(randomMax);
    }
    return array;
}


    public static void main(String[] args) {




            int MethodChoice = Integer.parseInt(JOptionPane.showInputDialog("What method would you like to use to sort the random numbers" + "\n" + "1 - Selection Sort" + "\n" + "2 - Bubble Sort" + "\n" + "3 - Insertion Sort" + "\n" + "4 - Quick Sort"));

            if (MethodChoice == 1) {

                    int iTotalCount = Integer.parseInt(JOptionPane.showInputDialog("What is the total number of integers?"));

                    int SortOrder = Integer.parseInt(JOptionPane.showInputDialog("1 - Ascending  "
                            + "2 - Descending"));


                    if (SortOrder == 2) {
                        int[] array = generateRandomArray(iTotalCount, 1001);
                        selectionSortReverse(array);

                        for(int count = array.length-1; count >= 0; count--)
                            System.out.print(array[count] + " ");
                        System.out.println("\n---------------------------------");

                        System.out.println("After sorting using the Selection Sort, " + "Using Descending Order" + " " + "the array is: ");

                        for(int i : array) {
                            System.out.print(i + " ");
                        }
                    } else if (SortOrder == 1) {
                        int[] array = generateRandomArray(iTotalCount, 1001);
                        selectionSort(array);

                        for(int count = array.length-1; count >= 0; count--)
                            System.out.print(array[count] + " ");
                        System.out.println("\n---------------------------------");


                        System.out.println("After sorting using the Selection Sort," + " the array is:");

                        for(int i : array) {
                            System.out.print(i + " ");
                        }
                    }

更新3

代码从选择开始工作 ---> 冒泡，插入没那么多。随机整数的打印与排序列表的格式相同。

代码如下:

 } else if (MethodChoice == 3) {
         if (SortOrder == 2) {
               insertionSortReverse(array);
                System.out.println("After sorting using the Insertion Sort, " + "Using Descending Order" + " " + "the array is: ");
            } else if (SortOrder == 1) {
                insertionSort(array);


                System.out.println("After sorting using the Insertion Sort," + " the array is:");

    }

    for (int i : array) {
        System.out.print(i + " ");
     }
    }

这是我的insertionSort()和insertionSortReverse()子函数:

public static void insertionSort(int data[]) {
    int insert;

    for (int next = 1; next < data.length; next++) {
      insert = data[next];
      int moveItem = next;

      while (moveItem > 0 && data[moveItem - 1] > insert) {
        data[moveItem] = data[moveItem - 1];
        moveItem--;
      }
      data[moveItem] = insert;
    }
  }

public static void insertionSortReverse(int data[]) {
    int insert;

    for (int next = 1; next < data.length; next++) {
      insert = data[next];
      int moveItem = next;

      while (moveItem < 0 && data[moveItem - 1] < insert) {
        data[moveItem] = data[moveItem - 1];
        moveItem--;
      }
      data[moveItem] = insert;
    }
  }

Answer 1

您的问题是当您点击 2 并继续时，它会按升序发布数字，这是因为您的升序代码周围没有 else 语句，或者您正在对数组进行反向排序，然后向后打印列表。另外，您发布的降序代码无论如何都对零列表进行排序...

private static int[] generateRandomArray(int size, int randomMax) {
    int[] array = new int[size];
    Random randomGenerator = new Random();
    for (int i = 0; i < size; i++) {
        array[i] = randomGenerator.nextInt(randomMax);
    }
    return array;
}

public static void main(String[] args) {
    int MethodChoice = Integer.parseInt(JOptionPane.showInputDialog("What method would you like to use to sort the random numbers" + "\n" + "1 - Selection Sort" + "\n" + "2 - Bubble Sort" + "\n" + "3 - Insertion Sort" + "\n" + "4 - Quick Sort"));
    int iTotalCount = Integer.parseInt(JOptionPane.showInputDialog("What is the total number of integers?"));
    int SortOrder = Integer.parseInt(JOptionPane.showInputDialog("1 - Ascending, " + "2 - Descending"));

    int[] array = generateRandomArray(iTotalCount, 1001);

    System.out.println("Randomly Generated number list: ");
    for (int i : array) {
        System.out.print(i + " ");
    }
    System.out.println("\n---------------------------------");

    if (MethodChoice == 1) {
        if (SortOrder == 2) {
            selectionSortReverse(array);
            System.out.println("After sorting using the Selection Sort, " + "Using Descending Order" + "the array is: ");
        } else if (SortOrder == 1) {
            selectionSort(array);
            System.out.println("After sorting using the Selection Sort," + " the array is:");
        }
    } else if (MethodChoice == 2) {
        // bubble-sort
    }

    for (int i : array) {
        System.out.print(i + " ");
    }
}