合并有序链表

将两个排序链表合并为一个新的排序链表

您在真实的面试中是否遇到过这个题？ 

Yes

样例

给出 1->3->8->11->15->null，2->null， 返回 1->2->3->8->11->15->null。

public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        ListNode head = null, p = l1, q = l2, k = null;        while (p != null && q != null) {            if (p.val < q.val) {                if (head == null) {                    head = p;                    k = head;                } else {                    k.next = p;                    k = k.next;                }                p = p.next;            } else {                if (head == null) {                    head = q;                    k = head;                } else {                    k.next = q;                    k = k.next;                }                q = q.next;            }        }        if (p == null) {            while (q != null) {                if (head == null) {                    head = q;                    k = head;                } else {                    k.next = q;                    k = k.next;                }                q = q.next;            }        } else {            while (p != null) {                if (head == null) {                    head = p;                    k = head;                } else {                    k.next = p;                    k = k.next;                }                p = p.next;            }        }        return head;    }