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Program to check if an Array is Palindrome or not using STL in C++

Last Updated : 11 Jul, 2025
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Given an array, the task is to determine whether an array is a palindrome or not, using STL in C++. Examples:

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

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

Approach:

  • Get the reverse of the Array using reverse() method, provided in STL.
  • Initialise flag to unset int flag = 0.
  • Loop the array till size n and check if the original array and the reversed array are same. If not set flag = 1
  • After the loop has ended, If flag is set the print "Not Palindrome" else print "Palindrome"

Below is the implementation of above Approach: 

CPP 
// C++ program to check if an Array
// is Palindrome or not using STL

#include <bits/stdc++.h>
using namespace std;

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

    // Create another array
    // to store the original array
    int arr2[n];
    memcpy(arr2, arr, n * sizeof(int));

    // Reverse the array
    reverse(arr, arr + n);

    // Check if the array is Palindrome
    for (int i = 0; i < n; i++)
        if (arr[i] != arr2[i]) {
            flag = 1;
            break;
        }

    // Print the result
    if (flag == 0)
        cout << "Palindrome\n";
    else
        cout << "Not Palindrome\n";
}

int main()
{
    // Get the array
    int arr[] = { 1, 2, 3, 2, 1 };

    // Compute the size
    int n = sizeof(arr) / sizeof(arr[0]);

    palindrome(arr, n);

    return 0;
}
Output:
Palindrome

Time complexity: O(n)
Auxiliary space: O(n)

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