# Merge Two Sorted Lists

Easy

## Question

Merge two sorted (ascending) linked lists and return it as a new sorted list. The new sorted list should be made by splicing together the nodes of the two lists and sorted in ascending order.

Example
Given 1->3->8->11->15->null, 2->null , return 1->2->3->8->11->15->null .

## Thinking

• One while loop to build a new list
• Some people consider about recursion, but I think the while loop is very straightforward.

## Solution

#### 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) {
if (l1 == null) {
return l2;
}
if (l2 == null) {
return l1;
}
ListNode merged = new ListNode(0);
ListNode tmp = merged;
while (l1 != null && l2!= null) {
if (l1.val < l2.val) {
tmp.next = l1;
l1 = l1.next;
} else {
tmp.next = l2;
l2 = l2.next;
}
tmp = tmp.next;
}
if (l1 != null) {
tmp.next = l1;
} else {
tmp.next = l2;
}
return merged.next;
}
}
``````