Print the last k nodes of the linked list in reverse order Recursive Approaches in C language

CServer Side ProgrammingProgramming

The task is to print the k nodes starting from the end of the linked list using recursive approach.

Recursive approach is the one in which the function call itself again and again till the call is being made and hence stores the result.

Let’s say, list contains the nodes 29, 34, 43, 56 and 88 and the value of k is 2 than the output will be the last k nodes such as 56 and 88.

Example

Linked List: 29->34->43->56->88
Input: 2
Output: 88 56

As specified the recursive approach should be used which will traverse the list from the end keeping track of the number of times the list is to be traversed and the recursive function will be called till the kth value by a pointer variable.

The below code shows the c implementation of the algorithm given.

Algorithm

START
   Step 1 -> create node variable of type structure
      Declare int data
      Declare pointer of type node using *next
   Step 2 -> Declare function as node* get(int data)
      Create newnode using malloc function
      Set newnode->data = data
      Set newnode->next = NULL
      return newnode
   step 3 -> Declare function void lastval(node* head, int& count, int k)
      IF !head
         Return
      Set lastval(head->next, count, k)
      Set count++
      IF (count <= k)
         Print head->data
   Step 4 -> In Main()
      Generate head using node* head = get(11)
      Set k and count to 0
      Call lastval(head,k,count)
STOP

Example

#include<stdio.h>
#include<stdlib.h>
// Structure of a node
struct node {
   int data;
   node* next;
};
// Function to get a new node
node* get(int data) {
   struct node* newnode = (struct node*)malloc(sizeof(struct node));
   newnode->data = data;
   newnode->next = NULL;
   return newnode;
}
//print the last k values of a node
void lastval(node* head, int& count, int k) {
   if (!head)
      return;
   lastval(head->next, count, k);
   count++;
   if (count <= k)
      printf("%d ", head->data);
}
int main() {
   node* head = get(11); //inserting elements into the list
   head->next = get(243);
   head->next->next = get(321);
   head->next->next->next = get(421);
   head->next->next->next->next = get(522);
   int k = 2, count = 0;
   printf(" last %d nodes of a list are :",k);
   // print last k nodes
   lastval(head, count, k);
   return 0;
}

Output

If we run above program then it will generate following output.

last 2 nodes of a list are :522 421
raja
Published on 22-Aug-2019 08:53:14
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