Question

它会使选择排序至少1，它排序插入排序很好，但似乎选择排序需要更多时间，我想不出来...... 它没有做适当的选择排序方法。我认为我的错误是在reorderselection方法中。

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.util.Random;

public class TwoSorts extends Applet {

private final int APPLET_WIDTH = 800, APPLET_HEIGHT = 600; // to make the applet size
private final int colNum = 15; // how many columns
int[] insertion = new int[colNum]; //insertion array for column heights
int[] selection = new int[colNum]; // selection array for column heights
public Random generator; // random numbers class
public int randomNum; // random number
public Button butn1 = new Button("Sort Arrays"); // buttons
public int selectionCount = 0; // how many times press the sort button
boolean selectionFlag, insertionFlag; // to stop looping when done

//**********************************************************************
//* initiates everything
//**********************************************************************
public void init()
{

  setBackground (Color.black);
  setSize(APPLET_WIDTH, APPLET_HEIGHT);
  generator = new Random();

  for (int column = 0; column < colNum; column++) // Creates the two arrays
  {
    randomNum = generator.nextInt(100) + 15;
    insertion[column] = randomNum;
    selection[column] = randomNum;
  }

  butn1.addActionListener(new Butn1Handler());
  butn1.setBackground(Color.blue);
  add(butn1);
}

//*************************************************************************
// Draws the columns
//************************************************************************
public void paint(Graphics g)
{
  g.setColor(Color.white); // debugging code
  g.drawString ("Count: " + selectionCount, 100, 495);

  g.drawString("Selection Sort", 25, 220);
  g.drawString("Insertion Sort", 25, 420);

  int xs = 50, ys = 100, width = 40, heights = 0; // for the loops
  int xi = 50, yi = 300, heighti = 0;

  if ( insertionFlag == false && selectionFlag == false)
  {
    for (int count = 0; count < colNum + 1; count++ )
    {
      g.setColor(Color.green);   
      heights = selection[count];
      heighti = insertion[count];
      g.fillRect(xs, ys, width, heights);
      g.fillRect(xi, yi, width, heighti);
      xs = xs + width + 2;
      xi = xi + width + 2;
    }
  }
  else
  {
    g.setColor(Color.white);
    g.drawString ("Sort is Done!", 5, 495);
    for (int count = 0; count < colNum + 1; count++ )
    {
      g.setColor(Color.gray);
      heights = selection[count];
      heighti = insertion[count];
      g.fillRect(xs, ys, width, heights);
      g.fillRect(xi, yi, width, heighti);
      xs = xs + width + 2;
      xi = xi + width + 2;
    }  
  }
}
//*****************************************************************************
//* Method to sort the array by Selection method
//******************************************************************************
public void reorderSelection()
{
  int min = selectionCount;
  int temp = 0;

   for (int scan = (selectionCount); scan < selection.length; scan++)
   { 
     if (selection[scan] < selection[min])
     min = scan;

       temp = selection[min];
       selection[min] = selection[selectionCount];
       selection[selectionCount] = temp;
   }
}
//*****************************************************************************
//* Method to sort the arrary by Insertion method
//******************************************************************************
public void reorderInsertion()
{
  int key = insertion[selectionCount];
  int position = selectionCount;
  while (position > 0 && key < (insertion[position-1]))
  {
    insertion[position] = insertion[position-1];
    position--;
  }
  insertion[position] = key;
}

//-----------------------------------------------------
// Button 1 Listener and instructions
//-----------------------------------------------------
public class Butn1Handler implements ActionListener
{
  public void actionPerformed(ActionEvent e)
  {
   reorderSelection();
   reorderInsertion();
   repaint();
   selectionCount++;
     if (selectionCount > 14)
       selectionFlag = true;
         if (selectionCount > 15)
           insertionFlag = true;

   }
 }
}

Answer 1

您的选择排序方法不正确。你需要一个内循环。

public void reorderSelection()
{
    int min = selectionCount;
    int temp = 0;

    for( int scan = selectionCount ; scan < selection.length - 1 ; scan++ )
    {
        min = scan;

        for(int i = scan + 1; i < selection.length ; i++)
        {
            if(selection[min] > selection[i])  min = i;
        }

        if(min != scan)
        {
            temp = selection[scan];
            selection[scan] = selection[min];
            selection[min] = temp;
        }
    }
}

twosorts只给我一个问题

1 个答案: