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Solution.java
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Solution.java
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package com.doslin.leetcode.queue._23;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Queue;
import com.doslin.leetcode.queue.base.ListNode;
/**
* Merge k Sorted Lists
* Created by doslin on 2017/12/21.
*/
public class Solution {
public ListNode mergeKLists(ListNode[] lists) {
if (null == lists || lists.length == 0) {
return null;
}
Queue<ListNode> queue = new PriorityQueue<>(lists.length, new Comparator<ListNode>() {
@Override
public int compare(ListNode o1, ListNode o2) {
return o1.val - o2.val;
}
});
ListNode fake = new ListNode(0);
ListNode tail = fake;
for (ListNode node : lists) {
if (null != node) {
queue.add(node);
}
}
while (!queue.isEmpty()) {
tail.next = queue.poll();
tail = tail.next;
if (null != tail.next) {
queue.add(tail.next);
}
}
return fake.next;
}
}