Total Accepted: 121007
Total Submissions: 469882
Difficulty: Hard
Contributors: Admin
Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
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(E) Merge Two Sorted Lists (M) Ugly Number II
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode mergeKLists(ListNode[] lists) {
return partition(lists, 0, lists.length - 1);
}
public ListNode partition(ListNode[] lists, int s, int e) {
if (s == e) return lists[s];
if (s < e) {
int m = (s + e) / 2;
ListNode l1 = partition(lists, s, m);
ListNode l2 = partition(lists, m + 1, e);
return merge(l1, l2);
} else {
return null;
}
}
public ListNode merge(ListNode l1, ListNode l2) {
ListNode res = new ListNode(0);
ListNode p = res;
if (l1 == null) return l2;
if (l2 == null) return l1;
while (l1 != null && l2 != null) {
if (l1.val < l2.val) {
p.next = new ListNode(l1.val);
l1 = l1.next;
} else {
p.next = new ListNode(l2.val);
l2 = l2.next;
}
p = p.next;
}
if (l1 != null) p.next = l1;
if (l2 != null) p.next = l2;
return res.next;
}
}
