最優化的快排，減少不必要的交換

只有當左邊的指大於pivot，右邊的值小於pivot才交換

 1 public static quickSortOptimized(int[] data,int left,int right){
 2
 3 int pivotIndex=(left+right)/2;
 4 int pivotValue=data[pivotIndex];
 5 int i=left;
 6 int j=right;
 7
 8 while(i<=j){
 9
10 //find left value greater than or equal to the pivotValue
11
12 if(data[i]<pivotValue) i++;
13
14 //find right value smaller than or equal to the pivotValue
15 if(data[j]>pivotVaule) j++;
16
17 //swapping the values in wrong places
18 if(i<=j){
19
20 swap(data,i,j);
21 i++;
22 j--;
23
24
25
26 }
27
28
29
30 }
31
32
33 //recursive
34
35 if(left<j){
36 quickSortOptimized(data,left,j);
37 }
38
39 if(right>i){
40
41 quickSortOptimized(data,i,right);
42 }
43 }