Merge k Sorted Lists(优先队列)

/Merge k Sorted Lists Total Accepted: 38333 Total Submissions: 181458 My Submissions Question Solution 
//Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
import java.util.Comparator;
import java.util.List;
import java.util.PriorityQueue;


//Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class MergekSortedLists {


public static void main(String[] args) {
// TODO 自动生成的方法存根

}
public ListNode mergeKLists(List lists) {
if(lists==null)
return null;
        PriorityQueue pq=new PriorityQueue(new Comparator(){
        //有正负就行
@Override
public int compare(ListNode o1, ListNode o2) {
// TODO 自动生成的方法存根
return o1.val-o2.val;
}
        });
        //遍历每一个
        for(ListNode list:lists)
        //有可能有空，空的不能加进去
        if(list!=null)
        pq.add(list);
        ListNode head=new ListNode(0);
        ListNode p=head;
        while(!pq.isEmpty()){
        ListNode cur=pq.poll();
        p.next=cur;
        if(cur.next!=null)
        pq.add(cur.next);
        p=cur;
        }
        return head.next;
    }
}