Java for Leetcode 025 Reverse Nodes in K-group

Given A linked list, reverse the nodes of a linked list K at a time and return its modified list.

If the number of nodes is not a multiple of K then left-out nodes in the end should remain as it is.

You may not alter the values in the nodes, and only nodes itself is changed.

Only constant memory is allowed.

For example,
Given This linked list:1->2->3->4->5

For k = 2, you should return:2->1->4->3->5

For k = 3, you should return:3->2->1->4->5

Problem Solving Ideas:

Similar to the k=2 situation, in view of the LIFO, can be implemented with a stack, the Java code is as follows:

Public ListNode Reversekgroup (ListNode head, int k) {ListNode result = new ListNode (0), index = result,temp=head;if (head = = NULL) return null; stack<integer> stack =new stack<integer> (), while (Temp!=null) {for (int i = 0; i < K; i++) {Stack.push (temp . val); temp = temp.next;if (temp = = null&&i<k-1) {index.next = Head;return result.next;}} while (!stack.isempty ()) {index.next=new ListNode (Stack.pop ()); index=index.next;head=head.next;}} return result.next;}

Java for Leetcode 025 Reverse Nodes in K-group