LeetCode OJ：Insertion Sort List （插入排序链表）

Sort a linked list using insertion sort.

用插入排序来排序一个list，额， 我写的好麻烦啊， debug了好久，至少提交了5次。。。写吐了快，先贴代码，写的也好乱啊：

 1 class Solution {
 2 public:
 3     ListNode* insertionSortList(ListNode* hed) {
 4         if (hed == NULL) return NULL;
 5         head = hed;
 6         ListNode * insertPosPrev;
 7         ListNode * afterP;
 8         ListNode * prev = head;
 9         ListNode * p = head->next;
10         while (p != NULL) {
11             if (p->val > prev->val){
12                 prev = p;
13                 p = p->next;
14                 continue;
15             }
16             insertPosPrev = findInsertPos(p);
17             if (insertPosPrev == NULL) {//插入头节点之前
18                 afterP = p->next;
19                 prev->next = afterP;
20                 p->next = head;
21                 head = p;
22                 p = afterP;
23                 continue;
24             }
25             else if (p != insertPosPrev->next) {
26                 afterP = p->next;
27                 prev->next = afterP;
28                 p->next = insertPosPrev->next;
29                 insertPosPrev->next = p;
30                 p = afterP;
31                 continue;
32             }
33             prev = p;
34             p = p->next;
35         }
36         return head;
37     }
38 
39 private:
40     ListNode * head;
41 
42     ListNode * findInsertPos(ListNode * end)
43     {
44         if (head->val >= end->val)
45             return NULL;    //如果插入点在头节点那么返回NULL
46         ListNode * prev = head;
47         ListNode * p = prev->next;
48         while (p != end) {
49             if (prev->val < end->val && p->val >= end->val)
50                 return prev;
51             prev = p;
52             p = p->next;
53         }
54         return prev;
55     }
56 };

这里贴一个大神的代码，有时间来看看，暂时还没看懂啊

 1 class Solution
 2 {
 3 public:
 4     ListNode *insertionSortList(ListNode *head)
 5     {
 6         if(head==NULL || head->next==NULL) return head;
 7         ListNode *cur=head;
 8         ListNode *helper=new ListNode(0);
 9         ListNode *pre;
10         while(cur)
11         {
12             ListNode *next=cur->next;
13             pre=helper;
14             while(pre->next!=NULL && pre->next->val<cur->val)
15             {
16                 pre=pre->next;
17             }
18             cur->next=pre->next;
19             pre->next=cur;
20             cur=next;
21         }
22         return helper->next;
23     }
24  
25 } ;

 下面是java写的，第一遍写的基本上可以不看了，写的太麻烦了，下面这个写的稍微简单一点，代码如下：

 1 public class Solution {
 2     public ListNode insertionSortList(ListNode head) {
 3         if(head == null) return null;
 4         ListNode helper = new ListNode(Integer.MIN_VALUE);//将第一个节点的值设置成最小的
 5         helper.next = head;
 6         ListNode p = head.next;
 7         ListNode pPre = head;
 8         ListNode scan = helper;
 9         while(p != null){
10             if(p.val >= pPre.val){
11                 p= p.next;
12                 pPre = pPre.next;
13             }else{
14                 while(p.val > scan.next.val){
15                     scan = scan.next;
16                 }
17                 if(p.val >= scan.val && p.val <= scan.next.val){
18                     ListNode tmp = scan.next;
19                     scan.next = p;
20                     pPre.next = p.next;
21                     p.next = tmp;
22                     p = pPre.next;
23                     scan = helper; // 将扫描节点重新放置到链表的前部
24                 }
25             }
26         }
27         return helper.next;
28     }
29 }

 

posted @ 2015-10-13 21:49  eversliver  阅读(278)  评论(0)  编辑  收藏  举报