LeetCode --- Insertion Sort List

题目链接

实现链表的插入排序

附上代码：

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode *insertionSortList(ListNode *head) {
12         if (head == NULL || head->next == NULL) {
13             return head;
14         }
15         // p: is pointer to the node to be inserted
16         // ppre: the previous node of p
17         ListNode *p = head->next, *ppre = head;
18         while (p != NULL) {
19             // find proper location of the next to be inserted node (that is p)
20             // "pre" holds the previous node of the proper location
21             ListNode *q = head, *pre = q;
22             while (q != p && q->val <= p->val) {
23                 pre = q;
24                 q = q->next;
25             }
26             // insert "p" before the first node
27             if (q == head) {
28                 pp->next = p->next;
29                 p->next = head;
30                 head = p;
31                 p = pp->next;
32             } else if (q != p) {
33                 pp->next = p->next;
34                 pre->next = p;
35                 p->next = q;
36                 p = pp->next;
37             } else {          // do not need move
38                 pp = p;
39                 p = p->next;
40             }
41         }
42         
43         return head;
44     }
45 };

 

posted on 2014-05-29 01:24  Stomach_ache  阅读(123)  评论(0)  编辑  收藏  举报

导航