Program to check if an Array is Palindrome or not

Given an array, the task is to determine whether an array is a palindrome or not.
Examples:

Input: arr[] = {3, 6, 0, 6, 3}
Output: Palindrome

Input: arr[] = {1, 2, 3, 4, 5}
Output: Not Palindrome

Approach:

• Initialise flag to unset int flag = 0.
• Loop the array till size n/2
• In a loop check if arr[i]! = arr[n-i-1] then set the flag = 1 and break
• After the loop has ended, If the flag is set to 1 then print “Not Palindrome” else print “Palindrome”

Below is the implementation of above Approach:

C++

// C++ Program to check whether the
// Array is palindrome or not

#include <iostream>
using namespace std;

void palindrome(int arr[], int n)
{
    // Initialise flag to zero.
    int flag = 0;

    // Loop till array size n/2.
    for (int i = 0; i <= n / 2 && n != 0; i++) {

        // Check if first and last element are different
        // Then set flag to 1.
        if (arr[i] != arr[n - i - 1]) {
            flag = 1;
            break;
        }
    }

    // If flag is set then print Not Palindrome
    // else print Palindrome.
    if (flag == 1)
        cout << "Not Palindrome";
    else
        cout << "Palindrome";
}

// Driver code.
int main()
{
    int arr[] = { 1, 2, 3, 2, 1 };
    int n = sizeof(arr) / sizeof(arr[0]);

    palindrome(arr, n);
    return 0;
}

Java

// Java Program to check whether the
// Array is palindrome or not

class GfG {

    static void palindrome(int arr[], int n)
    {
        // Initialise flag to zero.
        int flag = 0;

        // Loop till array size n/2.
        for (int i = 0; i <= n / 2 && n != 0; i++) {

            // Check if first and last element are different
            // Then set flag to 1.
            if (arr[i] != arr[n - i - 1]) {
                flag = 1;
                break;
            }
        }

        // If flag is set then print Not Palindrome
        // else print Palindrome.
        if (flag == 1)
            System.out.println("Not Palindrome");
        else
            System.out.println("Palindrome");
    }

    // Driver code.
    public static void main(String[] args)
    {
        int arr[] = { 1, 2, 3, 2, 1 };
        int n = arr.length;

        palindrome(arr, n);
    }
}

Python3

# Python3 Program to check whether the
# Array is palindromic or not
def palindrome(arr, n):

    # Initialise flag to zero.
    flag = 0;

    # Loop till array size n/2.
    i = 0;
    while (i <= n // 2 and n != 0):

        # Check if first and last element
        # are different. Then set flag to 1.
        if (arr[i] != arr[n - i - 1]):
            flag = 1;
            break;
        i += 1;

    # If flag is set then print Not Palindrome
    # else print Palindrome.
    if (flag == 1):
        print("Not Palindrome");
    else:
        print("Palindrome");

# Driver code.
arr = [ 1, 2, 3, 2, 1 ];
n = len(arr);

palindrome(arr, n);

# This code is contributed
# by chandan_jnu

C#

// C# Program to check whether the
// Array is palindromic or not
class GfG
{

    static void palindrome(int []arr, int n)
    {
        // Initialise flag to zero.
        int flag = 0;

        // Loop till array size n/2.
        for (int i = 0; i <= n / 2 && n != 0; i++)
        {

            // Check if first and last element are different
            // Then set flag to 1.
            if (arr[i] != arr[n - i - 1])
            {
                flag = 1;
                break;
            }
        }

        // If flag is set then print Not Palindrome
        // else print Palindrome.
        if (flag == 1)
            System.Console.WriteLine("Not Palindrome");
        else
            System.Console.WriteLine("Palindrome");
    }

    // Driver code.
    static void Main()
    {
        int []arr = { 1, 2, 3, 2, 1 };
        int n = arr.Length;

        palindrome(arr, n);
    }
}

// This code is contributed by chadan_jnu

PHP

<?php
// PHP Program to check whether the
// Array is palindrome or not

function palindrome($arr, $n)
{
    // Initialise flag to zero.
    $flag = 0;

    // Loop till array size n/2.
    for ($i = 0; $i <= $n / 2 &&
                 $n != 0; $i++)
    {

        // Check if first and last element are
        // different then set flag to 1.
        if ($arr[$i] != $arr[$n - $i - 1])
        {
            $flag = 1;
            break;
        }
    }

    // If flag is set then print Not Palindrome
    // else print Palindrome.
    if ($flag == 1)
        echo "Not Palindrome";
    else
        echo "Palindrome";
}

// Driver code.
$arr = array( 1, 2, 3, 2, 1 );
$n = count($arr);

palindrome($arr, $n);

// This code is contributed by chandan_jnu
?>

Javascript

<script>

// Javascript Program to check whether the
// Array is palindrome or not

function palindrome(arr, n)
{
    // Initialise flag to zero.
    let flag = 0;

    // Loop till array size n/2.
    for (let i = 0; i <= n / 2 && n != 0; i++) {

        // Check if first and last element are different
        // Then set flag to 1.
        if (arr[i] != arr[n - i - 1]) {
            flag = 1;
            break;
        }
    }

    // If flag is set then print Not Palindrome
    // else print Palindrome.
    if (flag == 1)
        document.write("Not Palindrome");
    else
        document.write("Palindrome");
}

// Driver code.

    let arr = [ 1, 2, 3, 2, 1 ];
    let n = arr.length;

    palindrome(arr, n);

// This code is contributed by Mayank Tyagi

</script>

Output:

Palindrome

Time complexity: O(n) where n is size of given array

Auxiliary space: O(1)