LintCode 链表排序

/**
* Definition of ListNode
* class ListNode {
* public:
*     int val;
*     ListNode *next;
*     ListNode(int val) {
*         this->val = val;
*         this->next = NULL;
*     }
* }
*/
class Solution {
public:
/**
* @param head: The first node of linked list.
* @return: You should return the head of the sorted linked list,
using constant space complexity.
*/
ListNode *sortList(ListNode *head) {
// write your code here

int a[1000005];
int top=0;
while(head!=NULL)
{
a[top++]=head->val;
head=head->next;
}
sort(a,a+top);
ListNode *dummy,*r,*s;
dummy=new ListNode(0);
r=dummy;
for(int i=0;i<top;i++)
{
s=new ListNode(a[i]);
r->next=s;
r=s;
}
return dummy->next;

}
};