LeetCode:Insertion Sort List

题目链接 链表的插入排序

Sort a linked list using insertion sort.

建议：为了操作方便，添加一个额外的头结点。代码如下： 本文地址

/**
* 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) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if(head == NULL || head->next == NULL)return head;
ListNode *p = head->next, *pstart = new ListNode(0), *pend = head;
pstart->next = head; //为了操作方便，添加一个头结点
while(p != NULL)
{
ListNode *tmp = pstart->next, *pre = pstart;
while(tmp != p && p->val >= tmp->val)
{tmp = tmp->next; pre = pre->next;}
if(tmp == p)pend = p;
else
{
pend->next = p->next;
p->next = tmp;
pre->next = p;
}
p = pend->next;
}
head = pstart->next;
delete pstart;
return head;
}
};

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