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Copy pathMergeKLists.java
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105 lines (87 loc) · 1.99 KB
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package moreAboutJava;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.PriorityQueue;
class ListNode {
int val;
ListNode next;
public ListNode(int val) {
this.val = val;
this.next = null;
}
}
/**
* merge K sorted list
* @author txie
*
*/
public class MergeKLists {
public static void main(String[] args) {
// TODO Auto-generated method stub
ArrayList<ListNode> lists = new ArrayList<ListNode>();
ListNode list1 = new ListNode(0);
ListNode temp1 = list1;
for (int i = 0; i < 5; i ++) {
temp1.next = new ListNode(i + 3);
temp1 = temp1.next;
}
printListNode(list1);
ListNode list2 = new ListNode(0);
ListNode temp2 = list2;
for (int i = 0; i < 3; i ++) {
temp2.next = new ListNode(i + 8);
temp2 = temp2.next;
}
printListNode(list2);
lists.add(list1);
lists.add(list2);
ListNode sortedList = mergeKLists(lists);
printListNode(sortedList);
}
private static void printListNode(ListNode list) {
// TODO Auto-generated method stub
if (list == null) {
System.out.println("list null");
} else {
while (list != null) {
System.out.print(list.val + " ");
list = list.next;
}
System.out.println();
}
}
private static ListNode mergeKLists(ArrayList<ListNode> lists) {
// TODO Auto-generated method stub
if (lists.size() == 0) {
return null;
}
PriorityQueue<ListNode> p = new PriorityQueue<ListNode>(lists.size(),
new Comparator<ListNode>() {
@Override
public int compare(ListNode o1, ListNode o2) {
// TODO Auto-generated method stub
if (o1.val > o2.val) {
return 1;
} else if (o1.val < o2.val) {
return -1;
} else
return 0;
}
});
for (ListNode node : lists) {
if (node != null)
p.add(node);
}
ListNode head = new ListNode(0);
ListNode q = head;
while (p.size() > 0) {
ListNode temp = p.poll();
q.next = temp;
if (temp.next != null) {
p.add(temp.next);
}
q = q.next;
}
return head.next;
}
}