Insertion Sort List(lintcode 173)

Description

Sort a linked list using insertion sort.

Example

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

Interface

/**
 * Definition for ListNode.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int val) {
 *         this.val = val;
 *         this.next = null;
 *     }
 * }
 */ 
public class Solution {
    /**
     * @param head: The first node of linked list.
     * @return: The head of linked list.
     */
    public ListNode insertionSortList(ListNode head) {
        // write your code here
    }
}

Solution

/**
 * Definition for ListNode.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int val) {
 *         this.val = val;
 *         this.next = null;
 *     }
 * }
 */ 
public class Solution {
    /**
     * @param head: The first node of linked list.
     * @return: The head of linked list.
     */
    public ListNode insertionSortList(ListNode head) {
        // write your code here
        ListNode dummy = new ListNode(0);

        while (head != null) {
            ListNode node = dummy;
            while (node.next != null && node.next.val <= head.val) {
                node = node.next;
            }

            ListNode temp = head.next;
            head.next = node.next;
            node.next = head;
            head = temp;
        }

        return dummy.next;
    }
}