题目描述
将两个升序链表合并为一个新的 升序 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 1：
输入：l1 = [1,2,4], l2 = [1,3,4] 输出：[1,1,2,3,4,4]
- 示例 2：
输入：l1 = [], l2 = [] 输出：[]
- 示例 3：
输入：l1 = [], l2 = [0] 输出：[0]
提示：
- 两个链表的节点数目范围是 [0, 50]
- 100 <= Node.val <= 100
- l1 和 l2 均按 非递减顺序 排列
来源：力扣（LeetCode） 链接：https://leetcode-cn.com/problems/merge-two-sorted-lists/ 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
package com.anthony.algorithm;
public class mergeTwoLists {
public static class ListNode {
int val;
ListNode next = null;
public ListNode(int val) {
this.val = val;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
ListNode head = this;
while (head != null){
sb.append(head.val + " ");
head = head.next;
}
return sb.toString();
}
}
public ListNode mergeTwoLists (ListNode l1, ListNode l2) {
if(l1 == null){
return l2;
}
if(l2 == null){
return l1;
}
ListNode dummy = new ListNode(0);
ListNode head = dummy;
while (l1 != null && l2 != null){
if(l1.val < l2.val){
head.next = l1;
l1 = l1.next;
}else{
head.next = l2;
l2 = l2.next;
}
head = head.next;
}
head.next = l1 == null ? l2 : l1;
return dummy.next;
}
public static void main(String[] args) {
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
l1.next.next = new ListNode(3);
ListNode l2 = new ListNode(1);
l2.next = new ListNode(2);
l2.next.next = new ListNode(4);
ListNode listNode = new mergeTwoLists().mergeTwoLists(l1, l2);
System.out.println(listNode.toString());
}
}
