11package linkedlists ;
22
3- import java .util .LinkedList ;
4- 53/**
64 * Given the pointer/reference to the head of a singly linked list,
75 * reverse it and return the pointer/reference to the head of reversed linked list.
@@ -16,29 +14,57 @@ static class Node{
1614 public int data ;
1715 public Node next ;
1816
19- Node (int a , Node next ){
17+ Node (int a ){
2018 this .data = a ;
21- this .next = next ;
19+ this .next = null ;
2220 }
2321 }
2422
23+ static void printList (Node node ) {
24+ while (node != null ) {
25+ System .out .print (node .data + " " );
26+ node = node .next ;
27+ }
28+ }
29+ 2530 public static void main (String args []){
2631
27- LinkedList < Integer > list1 = new LinkedList <> ();
28- list1 .add (7 );
29- list1 .add (14 );
30- list1 .add (21 );
31- list1 .add (28 );
32+ SinglyLinkedList list1 = new SinglyLinkedList ();
33+ list1 .head = new Node (7 );
34+ list1 .head . next = new Node (14 );
35+ list1 .head . next . next = new Node (21 );
36+ list1 .head . next . next . next = new Node (28 );
3237
33- System .out .println (list1 );
34- reverse_list (list1 );
38+ printList (head );
3539
40+ reverse_list (head );
41+ 42+ printList (reverse_list (head ));
3643 }
37- 38- 3944
40- private static void reverse_list (LinkedList <Integer > list1 ) {
41- // TODO Auto-generated method stub
45+ private static Node reverse_list (Node head2 ) {
46+ 47+ if (head2 ==null ||head2 .next ==null ){
48+ return null ;
49+ }
50+ 51+ Node start = head2 ;
52+ Node point = head2 .next ;
53+ 54+ start .next = null ;
55+ 56+ while (point != null ){
57+ Node temp = point .next ;
58+ System .out .println ("test2" );
59+ point .next = start ;
60+ 61+ point = temp ;
62+ 63+ }
64+ 65+ head2 = start ;
66+ return head2 ;
67+ 4268
4369 }
4470}
0 commit comments