1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

// @Title: 合并两个有序链表 (Merge Two Sorted Lists)
// @Author: 15816537946@163.com
// @Date: 2020-11-01 15:28:07
// @Runtime: 4 ms
// @Memory: 2.6 MB
/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func mergeTwoLists(l1 *ListNode, l2 *ListNode) *ListNode {
	/*
		if l1 == nil {
			return l2
		}
		if l2 == nil {
			return l1
		}

		tmp := new(ListNode)
		lo := tmp

		for l1 != nil && l2 != nil {
			var val int
			if l1.Val > l2.Val {
				val = l2.Val
				l2 = l2.Next
			} else {
				val = l1.Val
				l1 = l1.Next
			}

			lo.Next = &ListNode{Val: val}
			lo = lo.Next
		}

		if l1 != nil {
			lo.Next = l1
		} else {
			lo.Next = l2
		}

		return tmp.Next
	*/
	if l1 == nil {
		return l2
	} else if l2 == nil {
		return l1
	} else if l1.Val > l2.Val {
		l2.Next = mergeTwoLists(l1, l2.Next)
		return l2
	} else {
		l1.Next = mergeTwoLists(l1.Next, l2)
		return l1
	}
}