所以我想创建一个快速排序方法,但是,它没有正确排序。下面有我的输入和输出
原始阵列:
80.0 10.0 50.0 70.0 60.0 90.0 20.0 30.0 40.0 0.0
排序后的数组:
0.0 30.0 20.0 80.0 40.0 60.0 70.0 10.0 90.0 50.0快速排序不排序
我试图改变for循环for(int i = left; i < right; i++)
但现在的输出是:
0.0 20.0 30.0 40.0 80.0 10.0 60.0 90.0 70.0 50.0
public static void sort(double[] a)
{
quickSort(a, 0, a.length-1);
}
public static void quickSort(double [] a, int left, int right)
{
if (left < right)
{
int pivotIndex = (left+right)/2;
int pos = partition(a,left,right,pivotIndex);
quickSort(a,left,pos-1);
quickSort(a,pos+1,right);
}
}
private static int partition(double [] a, int left,int right,int pivotIndex)
{
double temp = a[pivotIndex];
a[pivotIndex] = a[right];
a[right] = temp;
int pos = left;//represents boundary between small and large elements
for(int i = left; i < right-1; i++)
{
if (a[i] <= a[pivotIndex])
{
double temp2 = a[i];
a[i] = a[pos];
a[pos] = temp2;
pos++;
}
}
double temp3 = a[pivotIndex];
a[pivotIndex] = a[pos];
a[pos] = temp3;
return pos;
}
将pivotIndex作为参数传递是没有用的,在分区内计算它会更有效率(并且避免所有交换的东西)......无论如何,分区的位置已经被分区返回。 – kriss 2010-02-23 09:30:51
我不想改变他原来的代码太多;我只是想纠正我看到的任何错误。重构交换是为了清晰而不是效率。 – polygenelubricants 2010-02-23 10:04:47