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
Example 2:
Input: lists = [] Output: []
Example 3:
Input: lists = [[]] Output: []
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 exceed104
.
SOLUTION
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
ListNode h = new ListNode(0);
ListNode ans=h;
while (l1 != null && l2 != null) {
if (l1.val < l2.val) {
h.next = l1;
h = h.next;
l1 = l1.next;
} else {
h.next = l2;
h = h.next;
l2 = l2.next;
}
}
if(l1==null){
h.next=l2;
}
if(l2==null){
h.next=l1;
}
return ans.next;
}
public ListNode mergeKLists(ListNode[] lists) {
if(lists.length==0){
return null;
}
int interval = 1;
while(interval<lists.length){
System.out.println(lists.length);
for (int i = 0; i + interval< lists.length; i=i+interval*2) {
lists[i]=mergeTwoLists(lists[i],lists[i+interval]);
}
interval*=2;
}
return lists[0];
}