三个list合并_21.合并两个有序链表

输入&＃xff1a;1->2->4, 1->3->4
输出&＃xff1a;1->1->2->3->4->4

package leetcode;
​
import java.util.List;
​
/*** 合并两个有序链表** 为了不影响原链表&＃xff0c;要通过new一个新链表的方式&＃xff0c;继承原链表* 注意保存原链表的头*/
public class Test21 {
​static class ListNode {
​int val;
​ListNode next;
​ListNode(int x) {val &＃61; x;}
​}
​public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {// 把原两个链表的内容放到第三个链表&＃xff0c;最后返回第三个链表的 头ListNode l3 &＃61; new ListNode(0);ListNode head &＃61; l3;while (l1 !&＃61; null && l2 !&＃61; null) {if (l1.val <&＃61; l2.val) {ListNode newNode &＃61; new ListNode(l1.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l1 &＃61; l1.next;} else {ListNode newNode &＃61; new ListNode(l2.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l2 &＃61; l2.next;}}// 可能存在l1、l2偏大&＃xff0c;某一个链表没有比较完&＃xff0c;需要把剩下的加入到l3while (l1 !&＃61; null) {ListNode newNode &＃61; new ListNode(l1.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l1 &＃61; l1.next;}while (l2 !&＃61; null) {ListNode newNode &＃61; new ListNode(l2.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l2 &＃61; l2.next;}
​return head.next;}
​public static void main(String[] args) {ListNode l1 &＃61; new ListNode(1);ListNode l2 &＃61; new ListNode(2);ListNode l3 &＃61; new ListNode(4);l1.next &＃61; l2;l2.next &＃61; l3;
​ListNode l11 &＃61; new ListNode(1);ListNode l22 &＃61; new ListNode(3);ListNode l33 &＃61; new ListNode(4);l11.next &＃61; l22;l22.next &＃61; l33;
​ListNode ans &＃61; mergeTwoLists(l1, l11);while (ans !&＃61; null) {System.out.print(ans.val);ans &＃61; ans.next;}}
}
​

输入:
[1->4->5,1->3->4,2->6
]
输出: 1->1->2->3->4->4->5->6

package leetcode;
​
/*** 合并K个排序链表*/
public class Test23 {
​static class ListNode {int val;ListNode next;
​ListNode(int x) {val &＃61; x;}}
​public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {ListNode l3 &＃61; new ListNode(0);ListNode head &＃61; l3;while (l1 !&＃61; null && l2 !&＃61; null) {if (l1.val <&＃61; l2.val) {ListNode newNode &＃61; new ListNode(l1.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l1 &＃61; l1.next;} else {ListNode newNode &＃61; new ListNode(l2.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l2 &＃61; l2.next;}}while (l1 !&＃61; null) {ListNode newNode &＃61; new ListNode(l1.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l1 &＃61; l1.next;}while (l2 !&＃61; null) {ListNode newNode &＃61; new ListNode(l2.val);l3.next &＃61; newNode;l3 &＃61; l3.next;l2 &＃61; l2.next;}return head.next;}
​public ListNode mergeKLists(ListNode[] lists) {if (lists.length &＃61;&＃61; 0) {return new ListNode(0).next;}
​if (lists.length &＃61;&＃61; 1) {return lists[0];}ListNode l1 &＃61; lists[0];// 循环比较&＃xff0c;将结果放到l1中&＃xff0c;然后又把l1拿出来用for (int i &＃61; 1; i ​}return l1;}
}
​