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.

Example:

Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4

题目分析:实现两个有序列链表的合并，以下是go语言实现

func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {
    var result *ListNode
    if l1 == nil {
        return l2
    }
    if  l2 == nil {
        return l1
    }
    if l1.Val < l2.Val{
        result = l1
        result.Next = mergeTwoLists(l1.Next,l2)
    }else{
        result = l2
        result.Next = mergeTwoLists(l2.Next,l1)
    }
    return result
}