问题描述

这段链表的快速排序的代码哪里出了问题，vs2010上调试不过

void myquicksort( node *phead, node *pback )
{

if( phead == pback )
{
return;
}
else
{
int key = phead->data ;
node *p1 = NULL;
for( node *p2 = phead->pNext; p2 != pback; p2 = p2->pNext )
{
if( p2->data < key )
{
p1 = p1->pNext;
int temp;
temp = p1->data;
p1->data = p2->data;
p2->data = temp;
}
}
int temp;
temp = p1->data;
p1->data = phead->data;
phead->data = temp;

        myquicksort( phead, p1 );
        myquicksort( p1->pNext, pback );

}
}

解决方案

p1空指针，没指向就使用了。

解决方案二：

 void myquicksort(node* &head, node* &end){
    node *head1, *head2, *end1, *end2;
    head1 =  head2 = end1 = end2  = NULL;   

    if( head == NULL ) return;

    node *p, *pre1, *pre2;
    p = pre1 = pre2 = NULL;

    int key = head->data;
    p = head->pNext; head->pNext = NULL;
    while( p != NULL ) {
        if ( p->data < key ){
            if( !head1 ) { head1 = p; pre1 = p; }
            else{ pre1->pNext = p; pre1 = p; }
            p = p->pNext;
            pre1->pNext = NULL;
        }
        else{
            if( !head2 ) { head2 = p; pre2 = p; }
            else { pre2->pNext = p; pre2 = p; }
            p = p->pNext;
            pre2->pNext = NULL;
        }
    }

    end1 = pre1; end2 = pre2;

    myquicksort(head1, end1);
    myquicksort(head2, end2);

    if( end1 && head2){
        end1->pNext = head; head->pNext = head2;
        head = head1;   end = end2;}

    else if(end1) {
        end1->pNext = head;
        end = head; head = head1; } 

    else if(head2){
        head->pNext = head2;    end = end2;}
}

解决方案三：

我知道了，漏了一句p1 = phead，p1要指向头指针！

解决方案四：

快速排序（VS2010）的代码