Check if all elements of the array are palindrome or not in Python

A palindrome array is an array that reads the same forwards and backwards. In Python, we can check if an array is a palindrome by comparing elements from both ends moving towards the center.

So, if the input is like nums = [10, 12, 15, 12, 10], then the output will be True because the array reads the same from left to right and right to left.

Algorithm

To solve this, we will follow these steps ?

• Get the size of the array
• Use a flag variable to track palindrome status
• Compare elements from start and end moving towards center
• If any pair doesn't match, it's not a palindrome
• Return the result

Using While Loop

Here's the step-by-step implementation using a while loop ?

def solve(nums):
    n = len(nums)
    is_palindrome = 0
    i = 0
    while i <= n // 2 and n != 0:
        if nums[i] != nums[n - i - 1]:
            is_palindrome = 1
            break
        i += 1
    if is_palindrome == 1:
        return False
    else:
        return True

nums = [10, 12, 15, 12, 10]
print(solve(nums))

True

Using Simple Comparison

A more Pythonic approach is to compare the array with its reverse ?

def is_palindrome_simple(nums):
    return nums == nums[::-1]

# Test with palindrome array
nums1 = [10, 12, 15, 12, 10]
print(f"Array {nums1} is palindrome: {is_palindrome_simple(nums1)}")

# Test with non-palindrome array
nums2 = [1, 2, 3, 4, 5]
print(f"Array {nums2} is palindrome: {is_palindrome_simple(nums2)}")

Array [10, 12, 15, 12, 10] is palindrome: True
Array [1, 2, 3, 4, 5] is palindrome: False

Using Two Pointers

An efficient approach using two pointers from both ends ?

def is_palindrome_two_pointers(nums):
    left, right = 0, len(nums) - 1
    
    while left < right:
        if nums[left] != nums[right]:
            return False
        left += 1
        right -= 1
    
    return True

# Test examples
test_arrays = [
    [10, 12, 15, 12, 10],
    [1, 2, 2, 1],
    [5],
    [1, 2, 3],
    []
]

for arr in test_arrays:
    result = is_palindrome_two_pointers(arr)
    print(f"Array {arr} is palindrome: {result}")

Array [10, 12, 15, 12, 10] is palindrome: True
Array [1, 2, 2, 1] is palindrome: True
Array [5] is palindrome: True
Array [1, 2, 3] is palindrome: False
Array [] is palindrome: True

Comparison

Conclusion

Use the two-pointer approach for optimal space efficiency, or array slicing for the most readable code. All methods effectively determine if an array is a palindrome by comparing elements symmetrically.