题目
链接
描述
合并 k 个升序的链表并将结果作为一个升序的链表返回其头节点。
示例1
输入：
[{1,2,3},{4,5,6,7}]
返回值：
{1,2,3,4,5,6,7}
示例2
输入：
[{1,2},{1,4,5},{6}]
返回值：
{1,1,2,4,5,6}
题解（合并）
import java.util.*;/** public class ListNode {* int val;* ListNode next = null;* public ListNode(int val) {* this.val = val;* }* }*/public class Solution {/*** 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可*** @param lists ListNode类ArrayList* @return ListNode类*/public ListNode mergeKLists (ArrayList<ListNode> lists) {// write code herereturn divide(lists, 0, lists.size() - 1);}//两个链表合并public ListNode mergeTwoLists (ListNode list1, ListNode list2) {ListNode dummy = new ListNode(0);ListNode cur = dummy;while (list1 != null && list2 != null) {if (list1.val < list2.val) {cur.next = list1;list1 = list1.next;} else {cur.next = list2;list2 = list2.next;}cur = cur.next;}cur.next = list1 != null ? list1 : list2;return dummy.next;}//将链表分成两半在合并//例如 从lists中取出list1,2,3,4,5,6 1,2合并成A 3,4合并成B 5,6合并成C 以此类推public ListNode divide (ArrayList<ListNode> lists, int left, int right) {if (left > right) {return null;}if (left == right) {return lists.get(left);}int mid = (left + right) / 2;return mergeTwoLists(divide(lists, left, mid), divide(lists, mid + 1, right));}
}
