QuickSort(快速排序)

......呵呵,写了比较久了,一直都没有发上来,这个最终测试的效率是500万数据排序需要1.7秒

 

这里提供的快速排序不是可以直接应用的，如果您要使用，请修改数据类型的比较操作为compare就可以了。

 

首先，来看看归并算法吧。

package selfimpr.datastruct.highsort; /** * * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:33:58 PM */ public class Amalgamate { public static long[] amalgamate(long[] array1, long[] array2) { int firstPointer,secondPointer, resultPointer; firstPointer = secondPointer = resultPointer = 0; long[] result = new long[array1.length + array2.length]; while(firstPointer < array1.length && secondPointer < array2.length) { if(array1[firstPointer] < array2[secondPointer]) { result[resultPointer++] = array1[firstPointer++]; } if(firstPointer >= array1.length) break; if(array2[secondPointer] <= array1[firstPointer]) { result[resultPointer++] = array2[secondPointer++]; } if(secondPointer >= array2.length) break; } for(; firstPointer<array1.length; firstPointer ++) { result[resultPointer++] = array1[firstPointer]; } for(; secondPointer<array2.length; secondPointer ++) { result[resultPointer++] = array2[secondPointer]; } return result; } }

归并算法是比较简单的，这里仅仅是将两个数组归并为一个新的数组返回，所以没有加注释。。。

 

下面是快速排序的代码,里面都有注释的.

package selfimpr.datastruct.highsort; /** * 快速排序算法 * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:39:09 PM */ public class QuickSort { /** * 计算复制的次数 */ public static int copyCount = 0; /** * 计算比较的次数 */ public static int compareCount = 0; /** * 排序算法 * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:39:43 PM * @param array 要排序的数组 */ public static void sort(long[] array) { sort(array, 0, array.length-1); } /** * 快速排序的递归算法. * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:40:10 PM * @param array 要排序的数组 * @param left 数组的做指针 * @param right 数组的右指针 */ public static void sort(long[] array, int left, int right) { //右指针<=左指针时说明当前分治得到的子数组长度为0 if(right - left <= 0) return ; //取当前子数组(也就是array数组中的left到right位置的数据)的最右面的数据为分治点. long division = array[right]; //将数组以division为分治点进行分治,得到分割点的index. int partitionIndex = partition(array, division, left, right); //对分治后的左子数组进行快速排序 sort(array, left, partitionIndex - 1); //将分治后的右子数组进行快速排序. sort(array, partitionIndex + 1, right); } public static void optimizeSort(long[] array, int left, int right) { if(right - left <= 0) return ; compareCount ++; long division = (array[left] + array[right] + array[(left+right)/2])/3; int partitionIndex = partition(array, division, left, right); sort(array, left, partitionIndex - 1); sort(array, partitionIndex + 1, right); } /** * 分治算法. * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:37:30 PM * @param array 要分治的数组 * @param division 分治的中间值 * @param left 数组的左指针 * @param right 数组的右指针 * @return 分治得到的数组界限 */ public static int partition(long[] array, long division, int left, int right) { int leftPointer = left-1; int rightPointer = right; while(true) { while(array[++leftPointer] < division) { compareCount ++; } while(rightPointer > left && array[--rightPointer] > division) { compareCount ++; } if(leftPointer < rightPointer) { swap(array, leftPointer, rightPointer); } else { break; } } swap(array, leftPointer, right); return leftPointer; } /** * 交换数组内leftPointer和rightPointer的数据. * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:38:44 PM * @param array * @param leftPointer * @param rightPointer */ private static void swap(long[] array, int leftPointer, int rightPointer) { long temp = array[leftPointer]; array[leftPointer] = array[rightPointer]; array[rightPointer] = temp; copyCount += 3; } }

 

下面是测试类,这里测试需要引入JUnit包.

package selfimpr.datastruct.highsort.test; import java.util.Random; import selfimpr.datastruct.highsort.QuickSort; import junit.framework.TestCase; /** * * @announce Keep all copyright, if you want to reprint, please announce source. * @author selfimpr * @mail [email protected] * @blog http://blog.csdn.net/lgg201 * @data May 14, 2009-9:45:55 PM */ public class QuickSortTest extends TestCase { Random random = new Random(); int length = 5000000; public void testQuickSort() { long[] array = new long[length]; for(int i=0; i<length; i++) { array[i] = random.nextInt(length); } // display2(array); long start = System.currentTimeMillis(); QuickSort.sort(array); System.out.println(System.currentTimeMillis() - start); // System.out.println(QuickSort.partition(array, array[array.length - 1], 0, array.length-1)); // display2(array); System.err.println("CompareCount: " + QuickSort.compareCount + "; CopyCount: " + QuickSort.copyCount); } public void display1(long[] array) { for(int i=0; i<array.length; i++) { System.err.print(array[i] + " "); if(i%5 == 0) System.err.println(); } System.err.println(); } public void display2(long[] array) { for(int i=0; i<array.length; i++) { System.err.print(array[i] + " "); } System.err.println(); } }

 

就这样了