LeetCode之Merge Two Sorted Lists

1、题目

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.

合并2个有序链表

2、代码实现

/**
 * 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) {
        if (l1 == null) {
return l2;
}
if (l2 == null) {
return l1;
}
ListNode head = new ListNode(0);
ListNode cur = head;
while (l1 != null && l2 != null) {
if (l1.val <= l2.val) {
//cur.val = l1.val;这样写会爆空指针异常
cur.next = l1;
l1 = l1.next;
} else {
//cur.val = l2.val;这样写会爆空指针异常
cur.next = l2;
//System.out.println(head.val);
l2 = l2.next;
}
cur = cur.next;
}
if (l1 != null) {
cur.next = l1;
} else {
System.out.println("l2 != null");
cur.next = l2;
}
        return head.next;
    }
}