LeetCode题解之Insertion Sort List

1、题目描述

2、题目分析

利用插入排序的算法即可。注意操作指针。

3、代码

 ListNode* insertionSortList(ListNode* head) {
         if (head == NULL || head->next == NULL)
             return head;
 
         ListNode *dummy = new ListNode();
         dummy->next = head;
         ListNode *pre = dummy;
         ListNode *p = head;
         ListNode *pn = head->next;
 
         while (pn != NULL) {
             pre = dummy;
             p = dummy->next;
             while (p->val < pn->val) {
                 p = p->next;
                 pre = pre->next;
             }
 
             ListNode *tmp = pn->next;
             pre->next = pn;
             pn->next = p;
 
             while (p->next != pn)
                 p = p->next;
             p->next = tmp;
             pn = tmp;
         }
 
         return dummy->next;
 
     }