Insertion Sort List

Source

• leetcode: Insertion Sort List

Sort a linked list using insertion sort.

Example
Given 1->3->2->0->null, return 0->1->2->3->null.

Java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode helper=new ListNode(0);
        ListNode pre=helper;
        ListNode current=head;
        while(current!=null) {
            pre=helper;
            while(pre.next!=null&&pre.next.val<current.val) {
                pre=pre.next;
            }
            ListNode next=current.next;
            current.next=pre.next;
            pre.next=current;
            current=next;
        }
        return helper.next;
    }
}