Merge K sorted Array

 package fbPractise;

 import java.util.*;

 public class MergeKLists {

     static class Pair {

         int listIndex;

         int idInList;

         int value;

         public Pair(int l, int id, int val) {

             this.listIndex = l;

             this.idInList = id;

             this.value = val;

         }

     }

     public static List<Integer> merge(List<List<Integer>> lists) {

         List<Integer> res = new ArrayList<Integer>();

         Comparator<Pair> comp = new Comparator<Pair>() {

             public int compare(Pair p1, Pair p2) {

                 return p1.value - p2.value;

             }

         };

         PriorityQueue<Pair> pq = new PriorityQueue<Pair>(1, comp);

         for (int i=0; i<lists.size(); i++) {

             Pair p = new Pair(i, 0, lists.get(i).get(0));

             pq.offer(p);

         }

         while (!pq.isEmpty()) {

             Pair pa = pq.poll();

             int index = pa.listIndex;

             int id = pa.idInList;

             if (id < lists.get(index).size()-1) {

                 pq.offer(new Pair(index, id+1, lists.get(index).get(id+1)));

             }

             res.add(pa.value);

         }

         return res;

     }

     /**

      * @param args

      */

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         List<Integer> l1 = Arrays.asList(1,2,2,3,6);

         List<Integer> l2 = Arrays.asList(1,4,5,7,8,9);

         List<Integer> l3 = Arrays.asList(3,3,3,5,10);

         List<List<Integer>> lists = new ArrayList<List<Integer>>();

         lists.add(new ArrayList<Integer>(l1));

         lists.add(new ArrayList<Integer>(l2));

         lists.add(new ArrayList<Integer>(l3));

         List<Integer> res = merge(lists);

         System.out.println(res);

     }

 }