21. 合并两个有序链表

package main

import "fmt"

type ListNode struct {
	Val  int
	Next *ListNode
}

// 创建链表
func createList(nums []int) *ListNode {
	head := &ListNode{}
	tail := head
	for i := 0; i < len(nums); i++ {
		node := &ListNode{Val: nums[i]}
		tail.Next = node
		tail = node
	}
	return head.Next
}

// 打印链表
func printList(head *ListNode) {
	for p := head.Next; p != nil; p = p.Next {
		fmt.Printf("%d ", p.Val)
	}
	fmt.Println()
}

func mergeTwoLists(list1 *ListNode, list2 *ListNode) *ListNode {
	newList := &ListNode{}
	tail := newList
	for list1 != nil && list2 != nil {
		if list1.Val < list2.Val {
			tail.Next = list1
			tail = list1
			list1 = list1.Next
		} else {
			tail.Next = list2
			tail = list2
			list2 = list2.Next
		}
	}
	if list1 != nil {
		tail.Next = list1
	} else {
		tail.Next = list2
	}
	return newList.Next
}

func main() {
	list1 := createList([]int{0, 2, 4})
	list2 := createList([]int{1, 5, 6})
	list := mergeTwoLists(list1, list2)
	printList(list)
}