Insertion Sort List

Sort a linked list using insertion sort.

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public 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.
        ListNode header = new ListNode(-1);
        header.next = null;
        if(head == null) return header.next;
        ListNode cur = head;
        while(cur != null){
            ListNode tmp = header.next;
            ListNode before = header;
            while(tmp != null && tmp.val < cur.val){
                before = before.next;
                tmp = tmp.next;
            }
            before.next = cur;
            ListNode a = cur.next;
            cur.next = tmp;
            cur = a;
        }
        return header.next;
    }
}

 第二遍：

public 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) return head;
        ListNode header = new ListNode(-1);
        ListNode cur = head, newbefore = header;
        while(cur != null){
            newbefore = header;
            while(newbefore.next != null && newbefore.next.val < cur.val){
                newbefore = newbefore.next;
            }
            ListNode newcur = newbefore.next;
            newbefore.next = cur;
            ListNode tmp = cur.next;
            cur.next = newcur;
            cur = tmp;
        }
        return header.next;
    }
}