Merge K Sorted Lists InterviewBit.java

/**
 * Definition for singly-linked list.
 * class ListNode {
 *     public int val;
 *     public ListNode next;
 *     ListNode(int x) { val = x; next = null; }
 * }
 */
public class Solution {
	public ListNode mergeKLists(ArrayList<ListNode> a) {
       PriorityQueue<Integer> pq = new PriorityQueue<Integer>();
       for(int i=0;i<a.size();i++) {
           ListNode runner = a.get(i);
           while(runner != null) {
               pq.add(runner.val);
               runner = runner.next;
           }
       }
       ListNode head = new ListNode(0);
       ListNode runner = head;
       while(pq.size() != 0) {
           runner.next = new ListNode(pq.poll());
           runner = runner.next;
       }
       
       return head.next;
	}
}