147 Insertion Sort List 链表插入排序

/**
 * 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* helper=new ListNode(-1);
        ListNode* cur=helper;
        while(head)
        {
            ListNode* next=head->next;
            cur=helper;
            while(cur->next&&cur->next->val<=head->val)
            {
                cur=cur->next;
            }
            head->next=cur->next;
            cur->next=head;
            head=next;
        }
        return helper->next;
    }
};