PROBLEM DESCRIPTION
Given an array of sorted linked lists of different sizes. The task is to merge them in such a way that after merging they will be a single sorted linked list.
SOLUTION
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class Solution {
Node mergeKLists(List<Node> arr) {
int n = arr.size();
if(n == 0)
return null;
if(n == 1)
return arr.get(0);
Node last = arr.get(n-1);
arr.remove(n-1);
Node rest = mergeKLists(arr);
return sortedMerge(last, rest);
}
Node sortedMerge(Node head1, Node head2) {
Node h1 = head1;
Node h2 = head2;
Node dummyHead = new Node(0);
Node tail = dummyHead;
while (h1 != null && h2 != null) {
Node temp = null;
if (h1.data < h2.data) {
temp = h1;
h1 = h1.next;
} else {
temp = h2;
h2 = h2.next;
}
temp.next = null;
tail.next = temp;
tail = tail.next;
}
if (h1 != null)
tail.next = h1;
else
tail.next = h2;
return dummyHead.next;
}
}