12 Check If an Array is a Palindrome

Question

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

Two Pointer

Logic

1. Use two pointers; One from the beginning and the other from the end until they cross.

   1. See if these values match

      1. if not return false

   2. Increment the first pointer and decrement the second pointer

2. return true

Code

bool isPalindrome(const vector<int> &arr) {
    int p1 = 0, p2 = arr.size() - 1;
    while(p1 < p2) 
        if(arr[p1++] != arr[p2--])
            return false;
    return true;
}

Complexity

Time Complexity: $O(n)$

Space Complexity: $O(1)$