(java)Merge Two Sorted Lists

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.

思路:首先创建一个空链表l3，如果比较l1和l2的大小，如果l1.val>l2.val，则将l2,链接到l3上，将l2向后移一个，否则就相反

代码如下(已通过leetcode)

public class Solution {

public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

if(l1==null) return l2;

if(l2==null) return l1;

ListNode p=l1;

ListNode q=l2;

ListNode a;

if(p.val>q.val) {

a=q;

q=q.next;

} else {

a=p;

p=p.next;

}

ListNode ans=a;

while(p!=null && q!=null) {

if(p.val>q.val) {

a.next=q;

q=q.next;

a=a.next;

} else {

a.next=p;

p=p.next;

a=a.next;

}

}

while(p!=null) {

a.next=p;

p=p.next;

a=a.next;

}

while(q!=null) {

a.next=q;

q=q.next;

a=a.next;

}

return ans;

}

}