Insertion Sort List -- leetcode

/**
* 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) {
ListNode fake(0);
while (head) {
ListNode *runner = &fake;
while (runner->next && runner->next->val < head->val)
runner = runner->next;

ListNode *bak = head->next;
head->next = runner->next;
runner->next = head;
head = bak;
}
return fake.next;
}
};