Leetcode 21:Merge Two Sorted Lists（golang实现合并两条已经排序的链表）

21.Merge Two Sorted Lists

题目链接：题目链接

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

解题代码：

golang语言

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {
    
	var head *ListNode
    		
    if l1==nil && l2==nil{
            return l1
        }
    if l1!=nil && l2==nil{    
        head=l1
        l1=l1.Next
    }
	if l2!=nil && l1==nil{    
        head=l2
        l2=l2.Next
    }
    if l2!=nil && l1!=nil{    
         if l1.Val<l2.Val{
			head=l1
			l1=l1.Next
		}else {
			head=l2
			l2=l2.Next
		}
    }
    
  
    var pre *ListNode=head
	var node *ListNode
	for l1!=nil &&l2!=nil {
		
		if l1.Val<l2.Val{
			node=l1
			l1=l1.Next
		}else {
			node=l2
			l2=l2.Next
		}
		pre.Next=node
		pre=node

	}
	if l1!=nil {
		node=l1
		pre.Next=node
		pre=node
        l1=l1.Next
		
	}
	if l2!=nil {
		node=l2
		pre.Next=node
		pre=node
        l2=l2.Next
		
	}
	return head

}