└── reverse linked list.txt


/reverse linked list.txt:
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  1 | import java.io.*;
  2 | import java.math.*;
  3 | import java.security.*;
  4 | import java.text.*;
  5 | import java.util.*;
  6 | import java.util.concurrent.*;
  7 | import java.util.function.*;
  8 | import java.util.regex.*;
  9 | import java.util.stream.*;
 10 | import static java.util.stream.Collectors.joining;
 11 | import static java.util.stream.Collectors.toList;
 12 | 
 13 | class SinglyLinkedListNode {
 14 |     public int data;
 15 |     public SinglyLinkedListNode next;
 16 | 
 17 |     public SinglyLinkedListNode(int nodeData) {
 18 |         this.data = nodeData;
 19 |         this.next = null;
 20 |     }
 21 | }
 22 | 
 23 | class SinglyLinkedList {
 24 |     public SinglyLinkedListNode head;
 25 |     public SinglyLinkedListNode tail;
 26 | 
 27 |     public SinglyLinkedList() {
 28 |         this.head = null;
 29 |         this.tail = null;
 30 |     }
 31 | 
 32 |     public void insertNode(int nodeData) {
 33 |         SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);
 34 | 
 35 |         if (this.head == null) {
 36 |             this.head = node;
 37 |         } else {
 38 |             this.tail.next = node;
 39 |         }
 40 | 
 41 |         this.tail = node;
 42 |     }
 43 | }
 44 | 
 45 | class SinglyLinkedListPrintHelper {
 46 |     public static void printList(SinglyLinkedListNode node, String sep, BufferedWriter bufferedWriter) throws IOException {
 47 |         while (node != null) {
 48 |             bufferedWriter.write(String.valueOf(node.data));
 49 | 
 50 |             node = node.next;
 51 | 
 52 |             if (node != null) {
 53 |                 bufferedWriter.write(sep);
 54 |             }
 55 |         }
 56 |     }
 57 | }
 58 | 
 59 | class Result {
 60 | 
 61 |     /*
 62 |      * Complete the 'reverse' function below.
 63 |      *
 64 |      * The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
 65 |      * The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
 66 |      */
 67 | 
 68 |     /*
 69 |      * For your reference:
 70 |      *
 71 |      * SinglyLinkedListNode {
 72 |      *     int data;
 73 |      *     SinglyLinkedListNode next;
 74 |      * }
 75 |      *
 76 |      */
 77 | 
 78 |     public static SinglyLinkedListNode reverse(SinglyLinkedListNode llist) {
 79 |     // Write your code here
 80 |     SinglyLinkedListNode prev = null;
 81 |     SinglyLinkedListNode current = llist;
 82 |     SinglyLinkedListNode next = null;
 83 | 
 84 |     
 85 |     while (current != null) {
 86 |         next = current.next; 
 87 |         current.next = prev; 
 88 |         prev = current;      
 89 |         current = next;     
 90 |     }
 91 | 
 92 |     
 93 |     return prev;
 94 | }
 95 |     
 96 | 
 97 | }
 98 | 
 99 | public class Solution {
100 |     public static void main(String[] args) throws IOException {
101 |         BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
102 |         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
103 | 
104 |         int tests = Integer.parseInt(bufferedReader.readLine().trim());
105 | 
106 |         IntStream.range(0, tests).forEach(testsItr -> {
107 |             try {
108 |                 SinglyLinkedList llist = new SinglyLinkedList();
109 | 
110 |                 int llistCount = Integer.parseInt(bufferedReader.readLine().trim());
111 | 
112 |                 IntStream.range(0, llistCount).forEach(i -> {
113 |                     try {
114 |                         int llistItem = Integer.parseInt(bufferedReader.readLine().trim());
115 | 
116 |                         llist.insertNode(llistItem);
117 |                     } catch (IOException ex) {
118 |                         throw new RuntimeException(ex);
119 |                     }
120 |                 });
121 | 
122 |                 SinglyLinkedListNode llist1 = Result.reverse(llist.head);
123 | 
124 |                 SinglyLinkedListPrintHelper.printList(llist1, " ", bufferedWriter);
125 |                 bufferedWriter.newLine();
126 |             } catch (IOException ex) {
127 |                 throw new RuntimeException(ex);
128 |             }
129 |         });
130 | 
131 |         bufferedReader.close();
132 |         bufferedWriter.close();
133 |     }
134 | }
135 | 


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