Program to check for palindrome
Definition & Explanation
The goal is to determine whether a given integer input is a palindrome. To achieve this, we will reverse the string representation of the input using loops and recursion and then check if it matches the original number.
Example:
Input: 151
Output: Palindrome
Way to solve
The aim is to determine whether a given input integer is a palindrome in the Java language. To accomplish this, we will reverse the number using the modulo and divide operators and then check if the reversed number matches the original number. Here are a few methods to check whether or not the number is a palindrome in Java:
- Method 1: Using Iteration
- Method 2: Using Recursion
In this code:
numberis the given input number.nis used to store a copy of the original number for comparison.reverseis used to store the reversed number.remainderis used to store the last digit in each iteration.- The while loop iterates through each digit of the number, rearranging them in reverse order.
- The code then checks if the reversed number matches the original number and prints the result accordingly.
C
Method 1 :
#include <stdio.h>
// Function to check if a number is a palindrome iteratively
int isPalindromeIterative(int number) {
int n = number;
int reverse = 0;
int remainder;
while (n > 0) {
remainder = n % 10;
reverse = reverse * 10 + remainder;
n = n / 10;
}
return (reverse == number);
}
int main() {
// Given input number
int number = 151;
// Check if the number is a palindrome iteratively
if (isPalindromeIterative(number)) {
printf("It's a palindrome\n");
} else {
printf("It is not a palindrome\n");
}
return 0;
}
Output :
It's a palindrome
Method 2 :
#include <stdio.h>
// Function to check if a number is a palindrome using recursion
int isPalindromeRecursive(int n, int reversed) {
// Base case: if there is no more digit to reverse
if (n == 0) {
return reversed;
}
// Get the last digit of the number
int lastDigit = n % 10;
// Add the last digit to the reversed number
reversed = reversed * 10 + lastDigit;
// Reverse the remaining part of the number
return isPalindromeRecursive(n / 10, reversed);
}
int main() {
// Given input number
int number = 151;
// Check if the number is a palindrome using recursion
if (isPalindromeRecursive(number, 0) == number) {
printf("It's a palindrome\n");
} else {
printf("It is not a palindrome\n");
}
return 0;
}
Output :
It's a palindrome
C++
Method 1 :
#include <iostream>
// Function to check if a number is a palindrome iteratively
bool isPalindromeIterative(int number) {
int n = number;
int reverse = 0;
int remainder;
while (n > 0) {
remainder = n % 10;
reverse = reverse * 10 + remainder;
n = n / 10;
}
return (reverse == number);
}
int main() {
// Given input number
int number = 151;
// Check if the number is a palindrome iteratively
if (isPalindromeIterative(number)) {
std::cout << "It's a palindrome" << std::endl;
} else {
std::cout << "It is not a palindrome" << std::endl;
}
return 0;
}
Output :
It's a palindrome
Method 2 :
#include <iostream>
// Function to check if a number is a palindrome using recursion
int isPalindromeRecursive(int n, int reversed) {
// Base case: if there is no more digit to reverse
if (n == 0) {
return reversed;
}
// Get the last digit of the number
int lastDigit = n % 10;
// Add the last digit to the reversed number
reversed = reversed * 10 + lastDigit;
// Reverse the remaining part of the number
return isPalindromeRecursive(n / 10, reversed);
}
int main() {
// Given input number
int number = 151;
// Check if the number is a palindrome using recursion
if (isPalindromeRecursive(number, 0) == number) {
std::cout << "It's a palindrome" << std::endl;
} else {
std::cout << "It is not a palindrome" << std::endl;
}
return 0;
}
Output :
It's a palindrome
JAVA
Method 1 :
public class Main {
public static void main(String[] args) {
// Given input number
int number = 151;
int n = number;
// Initialize variables to store the reverse and remainder
int reverse = 0;
int remainder;
// Loop until the entire number is processed
while (n > 0) {
// Extract the last digit using the modulo operator
remainder = n % 10;
// Rearrange digits in reverse order
reverse = reverse * 10 + remainder;
// Reduce the number by one digit using division
n = n / 10;
}
// Check if the reversed number matches the original number
if (reverse == number) {
System.out.println("It's a palindrome");
} else {
System.out.println("It is not a palindrome");
}
}
}
Output :
It's a palindromeMethod 2 :
public class Main {
// Function to check if a number is a palindrome using recursion
static boolean isPalindrome(int number) {
// Base case: if the number is a single digit, it is always a palindrome
if (number >= 0 && number < 10) {
return true;
}
// Get the last digit of the number
int lastDigit = number % 10;
// Reverse the remaining part of the number and compare with the last digit
return lastDigit == getReversed(number / 10, lastDigit);
}
// Function to get the reverse of a number using recursion
static int getReversed(int n, int reversed) {
// Base case: if there is no more digit to reverse
if (n == 0) {
return reversed;
}
// Get the last digit of the number
int lastDigit = n % 10;
// Add the last digit to the reversed number
reversed = reversed * 10 + lastDigit;
// Reverse the remaining part of the number
return getReversed(n / 10, reversed);
}
public static void main(String[] args) {
// Given input number
int number = 151;
// Check if the number is a palindrome using recursion
if (isPalindrome(number)) {
System.out.println("It's a palindrome");
} else {
System.out.println("It is not a palindrome");
}
}
}
Output :
It's a palindrome
Python
Method 1 :
# Function to check if a number is a palindrome iteratively
def is_palindrome_iterative(number):
n = number
reverse = 0
while n > 0:
remainder = n % 10
reverse = reverse * 10 + remainder
n = n // 10
return reverse == number
# Given input number
number = 151
# Check if the number is a palindrome iteratively
if is_palindrome_iterative(number):
print("It's a palindrome")
else:
print("It is not a palindrome")
Output :
It's a palindrome
Method 2 :
# Function to check if a number is a palindrome using recursion
def is_palindrome_recursive(n, reversed_number):
# Base case: if there is no more digit to reverse
if n == 0:
return reversed_number
# Get the last digit of the number
last_digit = n % 10
# Add the last digit to the reversed number
reversed_number = reversed_number * 10 + last_digit
# Reverse the remaining part of the number
return is_palindrome_recursive(n // 10, reversed_number)
# Given input number
number = 151
# Check if the number is a palindrome using recursion
if is_palindrome_recursive(number, 0) == number:
print("It's a palindrome")
else:
print("It is not a palindrome")
Output :
It's a palindrome