driver.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

/** Selection Sort Program (Figure 12.22)
 *  Author: David Riley
 *  Date: June, 2004
 */
public class Driver  {

	public Driver()   {
		double[] theArray;
		theArray = new double[30];
		
		for (int k = 0; k!=theArray.length; k++)   {
			theArray[k] = Math.random();
		}
		
		selectionSort( theArray );
		
		for (double d : theArray)   {
			System.out.println(d);
		}
	}
	
	/**	post:	arr is the same as arr@pre with item values permuted
	 *			and  for all j [0<=j<arr.length-1) [arr[j] >= arr[j+1]] 
	 */
	public void selectionSort( double[] arr )   {
		int selectedIndex;
        double selectedValue;
        int lastSorted = -1;
		while  ( lastSorted != arr.length-1 )   {
            selectedIndex = lastSorted+1;
            for (int k = lastSorted+2; k<arr.length; k++)   {
                if (arr[k] > arr[selectedIndex])   {
                    selectedIndex = k;
                }
            }
			lastSorted++;
			// swap arr[selectedIndex] with arr[lastSorted] 
			selectedValue = arr[selectedIndex];
			arr[selectedIndex] = arr[lastSorted];
			arr[lastSorted] = selectedValue;
		}
	}
}