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快速排序由C.A.R.Hoare(1962) 开发的,该算法在数组中选择一个称为主元(pivot)的元素,将数组分为两部分,是的第一部分中的所有元素都小于或等于主元,而第二部分的所有元素都大于主元。对第一部分递归地应用快速排序算法,然后对第二部分递归地应用快速排序算法。
package ss.sort; /** * 快速排序 * @author zhangss 2016-5-3 11:42:32 * */ public class QuickSort { public static void quickSort(int[] list){ quickSort(list, 0, list.length - 1); } private static void quickSort(int[] list, int first, int last){ if(last > first){ int pivotIndex = partition(list, first, last); quickSort(list, first, pivotIndex - 1); quickSort(list, pivotIndex + 1, last); } } private static int partition(int[] list, int first, int last){ int pivot = list[first]; // Choose the first element as the pivot int low = first + 1; // Index for forward search int high = last; // Index for backward search while(high > low){ // Search forward from left while(low <= high && list[low] <= pivot) low++; // Search forward from right while(low <= high && list[high] > pivot) high--; // Swap two elements in the list if(high > low){ int temp = list[high]; list[high] = list[low]; list[low] = temp; } } while(high > first && list[high] >= pivot) high--; // Swap pivot with list[high] if(pivot > list[high]){ list[first] = list[high]; list[high] = pivot; return high; }else{ return first; } } /** * A test method */ public static void main(String[] args) { int[] list = {2, 3, 2, 5, 6, 1, -2, 3, 14, 12}; quickSort(list); for(int i = 0; i < list.length; i++) System.out.print(list[i] + " "); } }
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原文地址:http://www.cnblogs.com/zsslll/p/5454494.html