鸡尾酒排序优化版

大部分元素有序时

冒泡排序一样，还可以继续优化，用标识符标识出无序区与有序区界限位置，用一个变量记录最后一个变换的位置，有序区内的元素不再参与比较

 public void sort() {
        int[] array={2,3,4,5,6,7,8,9,1};
        int lastRightExchangeIndex=0;
        int lastLeftExchangeIndex=0;
        int rightUnsortBorder = array.length-1;
        int leftUnsortBorder = 0;
 
        for(int i =0; i< array.length/2;i++){
            boolean isSorted = true; //标记是否已经有序
            //从左到右的循环
            for(int j = i; j<rightUnsortBorder;j++){
                if (array[j] > array[j+1]) {
                    int tem = array[j];
                    array[j]=array[j+1];
                    array[j+1] = tem;
                    isSorted=false;
                    lastRightExchangeIndex =j;
                }
            }
            rightUnsortBorder = lastRightExchangeIndex;
            if(isSorted){
                break;
            }
            //从右到左的循环
            isSorted=true;
            for(int j = array.length-i-1;j>leftUnsortBorder;j--){
                if(array[j]<array[j-1]){
                    int tem = array[j];
                    array[j]=array[j-1];
                    array[j-1] = tem;
                    isSorted=false;
                    lastLeftExchangeIndex = j;
                }
            }
            leftUnsortBorder = lastLeftExchangeIndex;
            if(isSorted){
                break;
            }
        }
 
        System.out.println(Arrays.toString(array));
    }