Leetcode:Insertion Sort List

Leetcode:Insertion Sort List

Sort a linked list using insertion sort.

插入排序：每步將一個待排序的紀錄，按其關鍵碼值的大小插入前面已經排序的文件中適當位置上，直到全部插入完為止。

實現代碼：

class Solution
{
public:
    ListNode *insertionSortList(ListNode *head)
    {
        if(head==NULL || head->next==NULL) return head;
        ListNode *cur=head;
        ListNode *helper=new ListNode(0);
        ListNode *pre;
        while(cur)
        {
            ListNode *next=cur->next;
            pre=helper;
            while(pre->next!=NULL && pre->next->valval)
            {
                pre=pre->next;
            }
            cur->next=pre->next;
            pre->next=cur;
            cur=next;
        }
        return helper->next;
    }
};