補充教學-氣泡排序法

2024/11/01閱讀時間約 9 分鐘

氣泡排序法(Bubble Sort)執行範例

BubbleSample.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="BubbleSample.aspx.cs" Inherits="BubbleSample" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            原本亂數產生的陣列：<br />
            <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
            <br /><br />
            排序後的陣列：<br />
            <asp:Label ID="Label3" runat="server" Text=""></asp:Label>
            <br /><br />
            由小到大排序每一次的過程<br />
            <asp:Label ID="Label2" runat="server" Text=""></asp:Label>
            
            <br /><br />
            <!--排序執行時間-->
            <asp:Label ID="Label4" runat="server" Text=""></asp:Label>
        </div>
    </form>
</body>
</html>

BubbleSample.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    int[] ary = new int[5];    //宣告陣列大小為10

    Random rnd = new Random();  //產生亂數初始值

    for (int i = 0; i < ary.Length; i++)
    {
        ary[i] = rnd.Next(1, 10);   //亂數產生，亂數產生的範圍是1~9
    }

    //顯示原本陣列內容
    showArray(Label1, ary);
    //排序
    BubbleSort(Label2, ary);
    //顯示陣列由小到大排序後結果
    showArray(Label3, ary);
}

void BubbleSort(Label lab, int[] ary)
{
    System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch();
    stopWatch.Start();  //計算程式時間開始

    int counter = 0;

    for (int i = 0; i < ary.Length; i++)
    {
        //因為下面比較會使用到j+1，所以j最大只能到陣列的倒數第二個，不然發生錯誤(陣列會超出範圍)
        for (int j = 0; j < ary.Length-1; j++)
        {
            lab.Text += $"ary[{j}] = {ary[j]}，ary[{j+1}] = {ary[j+1]}，";

            //由小到大；如果要改為由大到小，把 ary[j < ary[j+1] 改為 ary[j] > ary[j+1] 
            if (ary[j] > ary[j+1])
            {
                lab.Text += "swap，";
                swap(ary, j, j+1);
            }
            else
            {
                //顯示空格，排版用，畫面比較整齊
                lab.Text += "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;，";    
            }
            counter++;
            lab.Text += $"第{counter.ToString("00")}次排序後結果： ";
            showArray(lab, ary, true, j);
        }
        lab.Text += $"此輪(for j 迴圈)結束會找到ary[{ary.Length-1-i}]是陣列 0 - {ary.Length - 1 - i}中最大的數值 {ary[ary.Length - 1 - i]}<br>";
    }

    stopWatch.Stop();   //計算程式時間結束

    Label4.Text += $"排序執行次數: {counter} <br>";

    Label4.Text += $"排序執行時間(秒)：{(stopWatch.Elapsed.TotalMilliseconds / 1000).ToString("")} <br>";
}

//兩個值互相交換
void swap(int[] ary, int value1, int value2)
{
    int tmp = ary[value2];
    ary[value2] = ary[value1];
    ary[value1] = tmp;
}

//顯示陣列內容
//IsAdd：是一個選擇(optional)參數，可用可不用，預設值為false
//markIndex：會將陣列中的第markIndex與markIndex+1元素變成紅色，預設值為-1 (陣列起始值為0)
void showArray(Label lab ,  int[] ary, bool IsAdd = false, int markIndex = -1)
{
    string str = string.Empty;

    for (int i = 0; i < ary.Length; i++)
    {
        if(markIndex > -1 && (i == markIndex || i == (markIndex+1)))
        {
            str += $"<font color=red>{ary[i]}</font>，";
        }
        else
        {
            str += ary[i] + "，";
        }
    }

    if(IsAdd == false)
    {
        lab.Text = str;
    }
    else
    {
        lab.Text += str + "<br>";
    }
}