Find the string formed by joining k consecutive nodes of linked list

Last Updated : 02 Jun, 2021

Given an integer K and a linked list in which each node stores a single character. The task is to join every K consecutive nodes of the linked list to form a single word. Finally, print the string obtained by joining these words (space separated).
Examples:

Input: List = ‘a’ -> ‘b’ -> ‘c’ ->’d’ -> ‘e’ -> NULL, k = 3
Output: abc de
The first three nodes form the first word “abc”
and next two nodes form the second word “de”.
Input: List = ‘a’ -> ‘b’ -> ‘c’ -> ‘d’ -> ‘e’ -> ‘f’ -> NULL, k = 2
Output: ab cd ef

Approach: The idea is to traverse the linked list and keep adding character present at each node to the word formed so far. Keep track of the number of nodes traversed and when the count becomes equal to k, add the word formed so far to the resultant string, reset word to an empty string and reset the count to zero. Repeat this until the entire linked list is not traversed.
Below is the implementation of the above approach:

C++

// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
 
// Structure of a node
struct Node {
    char data;
    Node* next;
};
 
// Function to get a new node
Node* getNode(char data)
{
    // Allocate space
    Node* newNode = new Node;
 
    // Put in data
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}
 
// Function to find string formed by joining words
// obtained by joining k consecutive nodes of
// linked list.
string findKWordString(Node* head, int k)
{
    // Stores the final string
    string ans = "";
 
    // Keep track of the number of
    // nodes traversed
    int cnt = 0;
 
    // Stores the word formed by k consecutive
    // nodes of the linked list
    string word = "";
 
    while (head) {
 
        // Check if k nodes are traversed
        // If yes then add the word obtained
        // to the result string
        if (cnt == k) {
            if (ans != "") {
                ans = ans + " ";
            }
 
            ans = ans + word;
            word = "";
            cnt = 0;
        }
 
        // Add the current character to the word
        // formed so far and increase the count
        word = word + string(1, head->data);
        cnt++;
        head = head->next;
    }
 
    // Add the final word to the result
    // Length of the final word can be less than k
    if (ans != " ") {
        ans = ans + " ";
    }
    ans = ans + word;
 
    return ans;
}
 
// Driver code
int main()
{
 
    // Create list: a -> b -> c -> d -> e
    Node* head = getNode('a');
    head->next = getNode('b');
    head->next->next = getNode('c');
    head->next->next->next = getNode('d');
    head->next->next->next->next = getNode('e');
 
    int k = 3;
 
    cout << findKWordString(head, k);
 
    return 0;
}

Java

// Java implementation of the approach
class GFG{
 
// Class of a node
static class Node
{
    char data;
    Node next;
};
 
// Function to get a new node
static Node getNode(char data)
{
     
    // Allocate space
    Node newNode = new Node();
 
    // Put in data
    newNode.data = data;
    newNode.next = null;
    return newNode;
}
 
// Function to find string formed by 
// joining words obtained by joining 
// k consecutive nodes of linked list.
static String findKWordString(Node head, int k)
{
     
    // Stores the final string
    String ans = "";
 
    // Keep track of the number of
    // nodes traversed
    int cnt = 0;
 
    // Stores the word formed by k consecutive
    // nodes of the linked list
    String word = "";
 
    while (head != null)
    {
 
        // Check if k nodes are traversed
        // if yes then add the word obtained
        // to the result String
        if (cnt == k)
        {
            if (ans != "") 
            {
                ans = (ans + " ");
            }
 
            ans = ans + word;
            word = "";
            cnt = 0;
        }
 
        // Add the current character to the word
        // formed so far and increase the count
        word = word + head.data;
        cnt++;
        head = head.next;
    }
 
    // Add the final word to the result
    // Length of the final word can be
    // less than k
    if (ans != " ")
    {
        ans = (ans + " ");
    }
    ans = ans + word;
    return ans;
}
 
// Driver code
public static void main(String[] args)
{
 
    // Create list: a.b.c.d.e
    Node head = getNode('a');
    head.next = getNode('b');
    head.next.next = getNode('c');
    head.next.next.next = getNode('d');
    head.next.next.next.next = getNode('e');
 
    int k = 3;
 
    System.out.print(findKWordString(head, k));
}
}
 
// This code is contributed by GauravRajput1

Python3

# Python3 implementation of the approach
 
# Structure of a node
class Node:
    def __init__(self, d):
        self.data = d
        self.next = None
 
# Function to find formed by joining words
# obtained by joining k consecutive nodes of
# linked list.
def findKWordString(head,k):
     
    # Stores the final
    ans = ""
 
    # Keep track of the number of
    # nodes traversed
    cnt = 0
 
    # Stores the word formed by k consecutive
    # nodes of the linked list
    word = ""
 
    while (head):
 
        # Check if k nodes are traversed
        # If yes then add the word obtained
        # to the result
        if (cnt == k):
            if (ans != ""):
                ans = ans + " "
 
            ans = ans + word
            word = ""
            cnt = 0
 
        # Add the current character to the word
        # formed so far and increase the count
        word = word + head.data
        cnt += 1
        head = head.next
 
    # Add the final word to the result
    # Length of the final word can be less than k
    if (ans != " "):
        ans = ans + " "
    ans = ans + word
 
    return ans
 
# Driver code
if __name__ == '__main__':
 
 
    #Create list: a . b . c . d . e
    head = Node('a')
    head.next = Node('b')
    head.next.next = Node('c')
    head.next.next.next = Node('d')
    head.next.next.next.next = Node('e')
 
    k = 3
 
    print(findKWordString(head, k))
 
# This code is contributed by mohit kumar 29    

C#

// C# implementation of the approach
using System;
 
class GFG{
 
// Class of a node
class Node
{
    public char data;
    public Node next;
};
 
// Function to get a new node
static Node getNode(char data)
{
     
    // Allocate space
    Node newNode = new Node();
 
    // Put in data
    newNode.data = data;
    newNode.next = null;
    return newNode;
}
 
// Function to find string formed by 
// joining words obtained by joining 
// k consecutive nodes of linked list.
static String findKWordString(Node head, int k)
{
     
    // Stores the final string
    String ans = "";
 
    // Keep track of the number 
    // of nodes traversed
    int cnt = 0;
 
    // Stores the word formed by k 
    // consecutive nodes of the 
    // linked list
    String word = "";
 
    while (head != null)
    {
 
        // Check if k nodes are traversed
        // if yes then add the word obtained
        // to the result String
        if (cnt == k)
        {
            if (ans != "") 
            {
                ans = (ans + " ");
            }
 
            ans = ans + word;
            word = "";
            cnt = 0;
        }
 
        // Add the current character to the word
        // formed so far and increase the count
        word = word + head.data;
        cnt++;
        head = head.next;
    }
 
    // Add the readonly word to the result
    // Length of the readonly word can be
    // less than k
    if (ans != " ")
    {
        ans = (ans + " ");
    }
    ans = ans + word;
    return ans;
}
 
// Driver code
public static void Main(String[] args)
{
 
    // Create list: a.b.c.d.e
    Node head = getNode('a');
    head.next = getNode('b');
    head.next.next = getNode('c');
    head.next.next.next = getNode('d');
    head.next.next.next.next = getNode('e');
 
    int k = 3;
 
    Console.Write(findKWordString(head, k));
}
}
 
// This code is contributed by gauravrajput1

Javascript

<script>
 
// JavaScript implementation of the approach    
// Class of a node
class Node {
    constructor(val) {
        this.data = val;
        this.next = null;
    }
}
 
 
    // Function to get a new node
    function getNode( data) {
 
        // Allocate space
       var newNode = new Node();
 
        // Put in data
        newNode.data = data;
        newNode.next = null;
        return newNode;
    }
 
    // Function to find string formed by
    // joining words obtained by joining
    // k consecutive nodes of linked list.
     function findKWordString(head , k) {
 
        // Stores the final string
        var ans = "";
 
        // Keep track of the number of
        // nodes traversed
        var cnt = 0;
 
        // Stores the word formed by k consecutive
        // nodes of the linked list
        var word = "";
 
        while (head != null) {
 
            // Check if k nodes are traversed
            // if yes then add the word obtained
            // to the result String
            if (cnt == k) {
                if (ans != "") {
                    ans = (ans + " ");
                }
 
                ans = ans + word;
                word = "";
                cnt = 0;
            }
 
            // Add the current character to the word
            // formed so far and increase the count
            word = word + head.data;
            cnt++;
            head = head.next;
        }
 
        // Add the final word to the result
        // Length of the final word can be
        // less than k
        if (ans != " ") {
            ans = (ans + " ");
        }
        ans = ans + word;
        return ans;
    }
 
    // Driver code
     
 
        // Create list: a.b.c.d.e
        var head = getNode('a');
        head.next = getNode('b');
        head.next.next = getNode('c');
        head.next.next.next = getNode('d');
        head.next.next.next.next = getNode('e');
 
        var k = 3;
 
        document.write(findKWordString(head, k));
 
// This code contributed by aashish1995
 
</script>

Output:

abc de

Time Complexity: O(N)
Auxiliary Space: O(1)

Program for Nth node from the end of a Linked List

nik1996

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Practice Tags :

Find the string formed by joining k consecutive nodes of linked list

C++

Java

Python3

C#

Javascript

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