Home30 Days Of CodeHackerRank Day 18 : Queues and Stacks 30 days of code solution

HackerRank Day 18 : Queues and Stacks 30 days of code solution

Today we are going to solve HackerRank Day 18 : Queues and Stacks 30 days of code solution 30 days of code solution in CC++, Java, Python & Javascript.


Welcome to Day 18! Today we’re learning about Stacks and Queues

palindrome is a word, phrase, number, or other sequence of characters which reads the same backwards and forwards. Can you determine if a given string, s, is a palindrome?

To solve this challenge, we must first take each character in senqueue it in a queue, and also push that same character onto a stack. Once that’s done, we must dequeue the first character from the queue and pop the top character off the stack, then compare the two characters to see if they are the same; as long as the characters match, we continue dequeueing, popping, and comparing each character until our containers are empty (a non-match means s isn’t a palindrome).

Write the following declarations and implementations:

  1. Two instance variables: one for your stack, and one for your queue.
  2. void pushCharacter(char ch) method that pushes a character onto a stack.
  3. void enqueueCharacter(char ch) method that enqueues a character in the queue instance variable.
  4. char popCharacter() method that pops and returns the character at the top of the stack instance variable.
  5. char dequeueCharacter() method that dequeues and returns the first character in the queue instance variable.

Input Format

You do not need to read anything from stdin. The locked stub code in your editor reads a single line containing string s. It then calls the methods specified above to pass each character to your instance variables.


  • s is composed of lowercase English letters.

Output Format

You are not responsible for printing any output to stdout.
If your code is correctly written and s is a palindrome, the locked stub code will print The word, s, is a palindrome; otherwise, it will print The word, s, is not a palindrome.

Sample Input


Sample Output

The word, racecar, is a palindrome.

HackerRank Day 18 : Queues and Stacks 30 days of code solution

Queues and Stacks HackerRank Solution in C++

//Write your code here 
#include <iostream>
#include <stack>
#include <queue> 

using namespace std;

class Solution {
    //Write your code here
    std::stack<char> mystack;
    std::queue<char> myqueue;
        void pushCharacter(char ch){
        void enqueueCharacter(char ch){
        char popCharacter(){
            char top = mystack.top();
            return top;
        char dequeueCharacter(){
            char front = myqueue.front();
            return front;

Queues and Stacks HackerRank Solution in Java

public class Solution {
    LinkedList<Character> queue = new LinkedList();
    LinkedList<Character> stack = new LinkedList();
    public void pushCharacter(char ch){
    public void enqueueCharacter(char ch){
    public char popCharacter(){
        return stack.pop();
    public char dequeueCharacter(){
        return queue.remove();

More Exceptio Queues and Stacks HackerRank Solution in Python 3

#Write your code here

class Solution:

    def __init__(self):
        self.stack = []
        self.queue = []
    def pushCharacter(self, ch):
    def enqueueCharacter(self, ch):
    def popCharacter(self):
        return self.stack.pop()
    def dequeueCharacter(self):
        return self.queue.pop(0)

More Queues and Stacks HackerRank Solution in Javascript

//Write your code here
function Solution(){
  this.stack = [];
  this.queue = [];

Solution.prototype.pushCharacter = function pushCharacter (char) {

Solution.prototype.enqueueCharacter = function enqueueCharacter (char) {

Solution.prototype.popCharacter = function popCharacter () {
  return this.stack.pop();

Solution.prototype.dequeueCharacter  = function dequeueCharacter () {
  return this.queue.shift();

NEXT : HackerRank Day 19 : Interfaces 30 days of code solution

30 Days of Code HackerRank Solutions List – Day 0 to Day 29

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