Leetcode 021 Merge Two Sorted Lists

摘要：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.

Java：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

        ListNode p1 = l1;
        ListNode p2 = l2;

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

        while (p1 != null && p2 != null) {

            if (p1.val <= p2.val) {
                p.next = p1;
                p1 = p1.next;
            } else {
                p.next = p2;
                p2 = p2.next;
            }

            p = p.next;
        }

        if (p1 != null) {
            p.next = p1;
        }
        if (p2 != null) {
            p.next = p2;
        }

        return fakeHead.next;
    }
}