leetcode [147]Insertion Sort List

Sort a linked list using insertion sort.

A graphical example of insertion sort. The partial sorted list (black) initially contains only the first element in the list.
With each iteration one element (red) is removed from the input data and inserted in-place into the sorted list
 

Algorithm of Insertion Sort:

1. Insertion sort iterates, consuming one input element each repetition, and growing a sorted output list.
2. At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list, and inserts it there.
3. It repeats until no input elements remain.

Example 1:

Input: 4->2->1->3
Output: 1->2->3->4

Example 2:

Input: -1->5->3->4->0
Output: -1->0->3->4->5

题目大意：

利用插入排序对链表进行排序

解法：

待优化，效率较低。

java:

class Solution {
    public ListNode insertionSortList(ListNode head) {
        if(head==null||head.next==null) return head;
        ListNode newHead=new ListNode(-1);
        ListNode pre=newHead;
        ListNode cur=head;
        while(cur!=null){
            ListNode next=cur.next;
            while(pre.next!=null&& pre.next.val<cur.val){
                pre=pre.next;
            }
            cur.next=pre.next;
            pre.next=cur;
            cur=next;
            pre=newHead;
        }

        return newHead.next;
    }
}