题目

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]

分析

用一个指针去串联俩个链表，用一个指针记录新链表的头结点

java">public class LinkNode {int val;LinkNode next;public LinkNode(int data) {this.val = data;this.next = null;}
}
public class LinkList {LinkNode head;public LinkList() {this.head = null;}public LinkNode getHead() {return this.head;}//添加元素public void addNode(int data) {LinkNode node = new LinkNode(data);if (this.head == null) {this.head = node;} else {LinkNode cur = this.head;while(cur.next != null) {cur = cur.next;}cur.next = node;}}//正序打印public void print(LinkNode node) {while(node != null) {System.out.print(node.val);System.out.print(" ");node = node.next;}System.out.println();}public LinkNode merget(LinkNode nodea,LinkNode nodeb) {LinkNode head = new LinkNode(0);LinkNode pNode = new LinkNode(0);while(nodea != null && nodeb != null) {if(nodea.val < nodeb.val) {if(head.next==null) {head.next = nodea;}pNode.next = nodea;nodea = nodea.next;pNode = pNode.next;} else {if(head.next==null) {head.next = nodeb;}pNode.next = nodeb;nodeb = nodeb.next;pNode = pNode.next;}}while(nodea != null) {if(head.next==null) {head.next = nodea;}pNode.next = nodea;nodea = nodea.next;pNode = pNode.next;}while(nodeb != null) {if(head.next==null) {head.next = nodeb;}pNode.next = nodeb;nodeb = nodeb.next;pNode = pNode.next;}print(head.next);return head.next;}}
public class mergeTwoSortedLists {public static void main(String[] args) {LinkList list1 = new LinkList();list1.addNode(1);list1.addNode(2);list1.addNode(3);LinkList list2 = new LinkList();list2.addNode(1);list2.addNode(3);list2.addNode(4);list1.merget(list1.getHead(),list2.getHead());}}