Leetcode Merge k Sorted Lists problem solution in Java

In the Leetcode Merge k Sorted Lists problem solution in Java programming Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.

Merge all the linked-lists into one sorted linked-list and return it.

Example 1:

Input: lists = [[1,4,5],[1,3,4],[2,6]]
Output: [1,1,2,3,4,4,5,6]
Explanation: The linked lists are:
[
1->4->5,
1->3->4,
2->6
]
merging them into one sorted list:
1->1->2->3->4->4->5->6

Constraints:

• k == lists.length
• 0 <= k <= 104
• 0 <= lists[i].length <= 500
• -104 <= lists[i][j] <= 104
• lists[i] is sorted in ascending order.
• The sum of lists[i].length will not exceed 104.

Leetcode Merge k Sorted Lists problem solution in Java programming

class Solution {
    public ListNode mergeKLists(ListNode[] lists) {
        if (lists == null || lists.length == 0) {
            return null;
        }
        PriorityQueue<Integer> queue = new PriorityQueue<>();
        for (ListNode node : lists) {
            while (node != null) {
                queue.offer(node.val);
                node = node.next;
            }
        }
        return getNode(queue);
        
    }
     private  ListNode getNode(PriorityQueue<Integer> queue) {
        if (!queue.isEmpty()) {
            ListNode node = new ListNode(queue.poll(), null);
            node.next = getNode(queue);
            return node;
        }
        return null;
    }
}

Also read,

• Leetcode Merge k Sorted Lists problem solution in C++
• Leetcode Merge k Sorted Lists problem solution in C
• Leetcode Merge k Sorted Lists problem solution in Python
• Leetcode Merge k Sorted Lists problem solution in C#