LeetCode 021 Merge Two Sorted Lists

题目描述

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

代码

[code]    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

        if (l1 == null && l2 == null) {
            return null;
        }

        if (l1 == null) {
            return l2;
        }

        if (l2 == null) {
            return l1;
        }

        ListNode p = new ListNode(0);
        ListNode head = p;

        while (l1 != null && l2 != null) {

            if (l1.val < l2.val) {
                p.next = l1;
                l1 = l1.next;
            } else {
                p.next = l2;
                l2 = l2.next;
            }

            p = p.next;
        }

        if (l1 != null) {
            p.next = l1;
        } else {
            p.next = l2;
        }

        return head.next;
    }