我是一名编程学生,需要进行一个有关快速排序的字符串数组排序问题。在测试排序方法时,发现打印出来的字符串数组完全混乱无序,毫无规律可言。希望您能够帮助我找到代码错误或者我可能忽视的几个明显错误。提供的字符串数组列表包含以下65个名称:http://pastebin.com/jRrgeV1E,下面是排序方法的代码:
private static void quickSort(String[] a, int start, int end)
{
// index for the "left-to-right scan"
int i = start;
// index for the "right-to-left scan"
int j = end;
// only examine arrays of 2 or more elements.
if (j - i >= 1)
{
// The pivot point of the sort method is arbitrarily set to the first element int the array.
String pivot = a[i];
// only scan between the two indexes, until they meet.
while (j > i)
{
// from the left, if the current element is lexicographically less than the (original)
// first element in the String array, move on. Stop advancing the counter when we reach
// the right or an element that is lexicographically greater than the pivot String.
while (a[i].compareTo(pivot) < 0 && i <= end && j > i){
i++;
}
// from the right, if the current element is lexicographically greater than the (original)
// first element in the String array, move on. Stop advancing the counter when we reach
// the left or an element that is lexicographically less than the pivot String.
while (a[j].compareTo(pivot) > 0 && j >= start && j >= i){
j--;
}
// check the two elements in the center, the last comparison before the scans cross.
if (j > i)
swap(a, i, j);
}
// At this point, the two scans have crossed each other in the center of the array and stop.
// The left partition and right partition contain the right groups of numbers but are not
// sorted themselves. The following recursive code sorts the left and right partitions.
// Swap the pivot point with the last element of the left partition.
swap(a, start, j);
// sort left partition
quickSort(a, start, j - 1);
// sort right partition
quickSort(a, j + 1, end);
}
}
/**
* This method facilitates the quickSort method's need to swap two elements, Towers of Hanoi style.
*/
private static void swap(String[] a, int i, int j)
{
String temp = a[i];
a[i] = a[j];
a[j] = temp;
}