21.merge-two-sorted-lists.go

/*
 * @lc app=leetcode id=21 lang=golang
 *
 * [21] Merge Two Sorted Lists
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func mergeTwoLists(list1 *ListNode, list2 *ListNode) *ListNode {
    if list1 == nil {
		return list2
	}

	if list2 == nil {
		return list1
	}

	if list1.Val < list2.Val {
		list1.Next = mergeTwoLists(list1.Next, list2)
		return list1
	} else {
		list2.Next = mergeTwoLists(list1, list2.Next)
		return list2
	}
}
// @lc code=end