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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4.  
  5. class Test
  6. {
  7.    static class Node<T>
  8.    {
  9.       Node next;
  10.       T data;
  11.       Node(T data) { this.data = data; }
  12.       @Override
  13.       public String toString() { return data.toString(); }
  14.    }
  15.  
  16.    // reverses a linked-list starting at 'start', ending at min(end, len-th element)
  17.    // returns {first element, last element} with (last element).next = (len+1)-th element
  18.    static <T> Node<T>[] reverse(Node<T> start, int len)
  19.    {
  20.       Node<T> current = start;
  21.       Node<T> prev = null;
  22.       while (current != null && len > 0)
  23.       {
  24.          Node<T> temp = current.next;
  25.          current.next = prev;
  26.          prev = current;
  27.          current = temp;
  28.          len--;
  29.       }
  30.       start.next = current;
  31.       return new Node[]{prev, start};
  32.    }
  33.  
  34.    static <T> void reverseByBlock(Node<T> start, int k)
  35.    {
  36.       // reverse the complete list
  37.       start.next = reverse(start.next, Integer.MAX_VALUE)[0];
  38.       // reverse the individual blocks
  39.       Node<T>[] output;
  40.       Node<T> current = start;
  41.       while (current.next != null)
  42.       {
  43.          output = reverse(current.next, k);
  44.          current.next = output[0];
  45.          current = output[1];
  46.       }
  47.    }
  48.  
  49.    public static void main(String[] args)
  50.    {
  51.       Scanner scanner = new Scanner(System.in);
  52.       while (scanner.hasNextInt())
  53.       {
  54.          int k = scanner.nextInt();
  55.          // read the linked-list from console
  56.          Node<Integer> start = new Node<>(null);
  57.          Node<Integer> current = start;
  58.          int n = scanner.nextInt();
  59.          System.out.print("Input: ");
  60.          for (int i = 1; i <= n; i++)
  61.          {
  62.             current.next = new Node<>(scanner.nextInt());
  63.             current = current.next;
  64.             System.out.print(current.data + " ");
  65.          }
  66.          System.out.println("| k = " + k);
  67.          // reverse the list
  68.          reverseByBlock(start, k);
  69.          // display the list
  70.          System.out.print("Result: ");
  71.          for (Node<Integer> node = start.next; node != null; node = node.next)
  72.             System.out.print(node + " ");
  73.          System.out.println();
  74.          System.out.println();
  75.       }
  76.    }
  77. }
Success #stdin #stdout 0.13s 29340KB
comments (?)
stdin
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3 9 1 2 3 4 5 6 7 8 9
2 9 1 2 3 4 5 6 7 8 9
stdout
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Input: 1 2 3 4 5 6 7 8 9 | k = 3
Result: 7 8 9 4 5 6 1 2 3 

Input: 1 2 3 4 5 6 7 8 9 | k = 2
Result: 8 9 6 7 4 5 2 3 1
https://ideone.com/U8b33p
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
secret

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