Sort a linked list using insertion sort.
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *insertionSortList(ListNode *head) {
if(head == NULL)
return NULL;
ListNode *dumy = new ListNode(-1);
dumy->next = head;
ListNode *p = head->next;
head->next = NULL;
while(p)
{
ListNode *pNext = p->next;
ListNode *q = dumy;
while(q->next && q->next->val < p->val)
q = q->next;
p->next = q->next;
q->next = p;
p = pNext;
}
p = dumy->next;
delete dumy;
return p;
}
};