【leetcode】Insertion Sort List

Insertion Sort List

/**
* 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 || head->next==NULL) return head;
ListNode *p,*q;
p=head;
q=head->next;
while(q)
{
if(q->val<p->val)
{
ListNode *innerp,*innerq;
innerp=head;
innerq=head->next;
while(q->val>innerq->val)
{
innerp=innerp->next;
innerq=innerq->next;
}
if(innerp==head && innerp->val > q->val)
{
p->next=q->next;
q->next=head;
head=q;
}
else
{
p->next=q->next;
innerp->next=q;
q->next=innerq;
}
q=p->next;
}
else
{
p=p->next;
q=q->next;
}
}
return head;
}
};