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// @Title: 合并两个有序链表 (Merge Two Sorted Lists)
// @Author: 15816537946@163.com
// @Date: 2020-06-25 07:15:36
// @Runtime: 0 ms
// @Memory: 2.6 MB
/*
 * @lc app=leetcode.cn id=21 lang=golang
 *
 * [21] 合并两个有序链表
 *
 * https://leetcode-cn.com/problems/merge-two-sorted-lists/description/
 *
 * algorithms
 * Easy (57.14%)
 * Likes:    619
 * Dislikes: 0
 * Total Accepted:    109.8K
 * Total Submissions: 192.1K
 * Testcase Example:  '[1,2,4]\n[1,3,4]'
 *
 * 将两个有序链表合并为一个新的有序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
 *
 * 示例:
 *
 * 输入:1->2->4, 1->3->4
 * 输出:1->1->2->3->4->4
 *
 *
 */
/**
 * 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
	}
	ret := new(ListNode)
	cur := ret
	for l1 != nil && l2 != nil {
		var val int
		if l1.Val < l2.Val {
			val = l1.Val
			l1 = l1.Next
		} else {
			val = l2.Val
			l2 = l2.Next
		}
		cur.Next = &ListNode{Val: val}
		cur = cur.Next
	}

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

	return ret.Next
}