Question

首先，我看到了一个与C ++有关的类似问题，但我并不太了解它 - 而且我的问题是关于Java。

基本上我编写了两个方法，可以在解析的数组中使用SelectionSort和BubbleSort。虽然我相信我的方法正常工作（我已经运行了测试，他们都按升序对数字进行了排序），但我不是确定我是否正确计算比较次数和数字交换次数。如果有人能够在下面测试我的代码并提供一些反馈，我将非常感激。

注意：我可以压缩我的Java项目文件，并在需要时将其发送给任何人。

BubbleSort方法：

public String bubbleSort(int[] numbers)
    {
        System.out.println("******|Bubble Sort|******");
        StringBuilder originalArray = new StringBuilder();

        for(int i = 0; i <= numbers.length - 1; i++)
        {
            originalArray.append(numbers[i] + " ");
        }
        System.out.println("Original array: " + originalArray);
        int temp; // temporary variable

        //Set boolean variable to true, 
        //to allow the first pass.
        boolean pass = true;

        int comparisons = 0;
        int swaps = 0;

        //While a pass can be made, 
        while(pass)
        {
            //Set the boolean value to false, 
            //indicating a number swap could 
            //be made.
            pass = false;

            for(int i = 0; i < numbers.length - 1; i++)
            {
                //increment the number of comparisons by 1.
                comparisons++;
                if(numbers[i] > numbers[i+1])
                {
                    temp = numbers[i];
                    numbers[i] = numbers[i + 1];
                    numbers[i+1] = temp;

                    //increment the amount of swaps made by 1, 
                    //to put numbers in correct order.
                    swaps++;
                    pass = true;
                }
            }
        }

        //Create a StringBuilder object - to hold 
        //the output of sorted numbers.
        StringBuilder sb = new StringBuilder();

        //Loop through the now sorted array - appending 
        //each subsequent number in the array to the 
        //StringBuilder object.
        for(int i = 0; i < numbers.length; i++)
        {
            sb.append(numbers[i] + " ");
        }

        //Return the final results of the sorted array.
        return "Sorted Array (asc): " + sb.toString() + "\nComparisons made: " + comparisons 
                + "\nSwaps made: " + swaps;
    }

SelectionSort方法

public String selectionSort(int[] numbers)
    {
        System.out.println("******|Selection Sort|******");
        StringBuilder originalArray = new StringBuilder();

        int comparisons = 0;
        int swaps = 0;

        for(int i = 0; i <= numbers.length - 1; i++)
        {
            originalArray.append(numbers[i] + " ");
        }
        System.out.println("Original array: " + originalArray);

        //Declare variable to hold first element
        int first;

        //declare temporary variable, to be used in 
        //swapping integers.
        int temp;

        for(int x = numbers.length - 1; x > 0; x--)
        {
            first = 0;
            comparisons++;
            for(int y = 1; y <= x; y++)
            {
                //comparisons++;
                if(numbers[y] > numbers[first])
                {
                    first = y;
                    //comparisons++;
                    swaps++;
                }
                temp = numbers[first];
                numbers[first] = numbers[x];
                numbers[x] = temp;
                //swaps++;
            }
        }

        //Create a StringBuilder object - to hold 
        //the output of sorted numbers.
        StringBuilder sb = new StringBuilder();

        //Loop through the now sorted array - appending 
        //each subsequent number in the array to the 
        //StringBuilder object.
        for(int i = 0; i < numbers.length; i++)
        {
            sb.append(numbers[i] + " ");
        }

        //Return the final results of the sorted array.
        return "Sorted Array (asc): " + sb.toString() + "\nComparisons made: " + comparisons 
                + "\nSwaps made: " + swaps;
    }

Answer 1

对于BUBBLE SORT：

主要比较 - ＆gt; （n *（n-1））/ 2

项目分配（互换） - ＆gt; 3 *（n-1）

选择排序：

主要比较 - ＆gt; （n *（n-1））/ 2 （与气泡相同）

项目分配（互换） - ＆gt; （n *（n-1））/ 4

（请注意 n 是您的数组大小的数量）

选择排序和冒泡排序 - 如何计算比较次数和数量交换？

1 个答案: