leetcode_c++：链表：Insertion Sort List(147)

ListNode *insertionSortList(ListNode *head) {
if(head == NULL) return head;
ListNode *p = new ListNode(-1);
p->next = head;
ListNode *pre = head;
ListNode *cur = pre->next;
while(cur){

if(cur->val >= pre->val){
pre = cur;
cur = cur->next;
}else{
ListNode *insertPre = p;
ListNode *insertCur = p->next;
while(insertCur->val < cur->val){
insertPre = insertCur;
insertCur = insertCur->next;
}
pre->next = cur->next;
cur->next = insertCur;
insertPre->next = cur;
cur = pre->next;
}

}
head = p->next;
return head;
}