LeetCode21- 合并两个有序链表

将两个有序链表合并为一个新的有序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。 

示例：

输入：1->2->4, 1->3->4
输出：1->1->2->3->4->4

代码：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode list;
        ListNode head = new ListNode( 0 );
        list = head;
        ListNode p = l1 , q = l2;
        while( l1 != null && l2 != null ) {
            if ( l1.val < l2.val ) {
                head.next = new ListNode( l1.val );
                l1 = l1.next;
                head = head.next;
            }
            else {
                head.next = new ListNode( l2.val );
                l2 = l2.next;
                head = head.next;
            }
        }
        while( l1 != null ) {
            head.next = new ListNode( l1.val );
            l1 = l1.next;
            head = head.next;
        }
        while ( l2 != null ) {
            head.next = new ListNode( l2.val );
            l2 = l2.next;
            head = head.next;
        }
        
        return list.next;
    }
}

 运行结果：