java版快速排序

Java非递归方式实现快速排序

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package sort.algorithm; import java.util.Stack; //快速排序的非递归实现，利用系统的栈stack public class QuickSortNonRecursion {      public static void main(String[] args) {          QuickSortNonRecursion qsnr = new QuickSortNonRecursion();          int[] array = {0, 2, 11, 121, 18, 99, 3, 5, 101, 22, 9, 100};          qsnr.quicksort(array);           for (int i : array) {                 System.out.print(i + "  ");           }         }                           public void quicksort(int[] array) {             if (array == null || array.length == 1) return;             //存放开始与结束索引             Stack<Integer> s = new Stack<Integer>();              //压栈                    s.push(0);              s.push(array.length - 1);              //利用循环里实现             while (!s.empty()) {                  int right = s.pop();                  int left = s.pop();                  //如果最大索引小于等于左边索引，说明结束了                 if (right <= left) continue;                                            int i = partition(array, left, right);                  if (left < i - 1) {                     s.push(left);                     s.push(i - 1);                 }                  if (i + 1 < right) {                     s.push(i+1);                     s.push(right);                 }             }          }         //找到轴心，进行交换         public int partition (int[] data, int first, int end)         {             int temp;             int i=first,j=end;             if(first<end)             {                 temp=data[i];                 //当i=j的时候，则说明扫描完成了                 while(i<j)                 {                     //从右边向左边扫描找到一个小于temp的元素                     while(j>i&&data[j]>temp)j--;                     if(i<j)                     {                         //将该元素赋值给temp                         data[i]=data[j];                         //赋值后就应该将i+1指向下一个序号                         i++;                     }                                                 //然后从左边向右边开始扫描，找到一个大于temp的元素                     while(i<j&&temp>data[i])i++;                     if(i<j)                     {                         //将该元素赋值给temp                         data[j]=data[i];                         //赋值后就应该将j-1指向前一个序号                         j--;                     }                 }                 //将轴数据放在i位置中                 data[i]=temp;             }             return i;         }     }