Day-43-Array-Rotation-Checker

Day 43/100 - Python Program to Check Array Rotation and Perform Operations

Check Array Rotation

A program to determine if one array is a rotation of another, returning specific mathematical results based on the evaluation while handling edge cases gracefully.

📝 Description

This program prompts the user to input two arrays (lists of numbers) and checks if the second array is a valid rotation of the first.

To solve the rotation problem efficiently, it uses a clever concatenation trick: it duplicates the first array and appends it to itself (arr1 + arr1). If the second array is a true rotation, it will exist as an exact contiguous sublist within that doubled array.

Beyond just returning True or False, this script executes specific operations based on the result:

• If the array is a rotation, it returns the sum of all elements in the first array.
• If the array is not a rotation, it returns the maximum value found in the first array.
• It includes strict validation: if the inputs are not lists, are of unequal length, or are empty, it immediately aborts the operation and returns "No proceed".

The driver code utilizes a while loop for continuous testing and ast.literal_eval to safely parse the user's string input into a native Python list without using the dangerous eval() function.

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🎯 Problem Statement

Input:

• Input 1: A string formatted as a Python list representing the first array (arr1), e.g., [1, 2, 3].
• Input 2: A string formatted as a Python list representing the second array (arr2), e.g., [3, 1, 2].

Output:

• The calculated integer result (Sum or Max) or the specific string "No proceed".

Rules:

1. The program must accept two inputs parsed safely into lists.
2. Validation: Check if both inputs are lists, if they have the exact same length, and if they are not empty. If any condition fails, return "No proceed".
3. Core Logic: Concatenate arr1 with itself to form a master search space.
4. Iterate through the master array to check if arr2 perfectly matches any slice of length(arr1).
5. If a match is found (it is a rotation), return the sum of arr1 (sum(arr1)).
6. If no match is found (it is not a rotation), return the highest value in arr1 (max(arr1)).

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💡 Examples

Example 1 (Valid Rotation)

Input:

[1, 2, 3, 4]
[3, 4, 1, 2]

Output:

Hasil: 10

Explanation: [3, 4, 1, 2] is a valid rotation of [1, 2, 3, 4]. Because it is a rotation, the program calculates the sum of the elements: $1 + 2 + 3 + 4 = 10$.

Example 2 (Not a Rotation)

Input:

[1, 2, 3, 4, 5]
[5, 4, 3, 2, 1]

Output:

Hasil: 5

Explanation: The second array is reversed, but not rotated (a rotation shifts elements without changing their relative sequence). Since it is not a rotation, the program returns the maximum value of the first array, which is 5.

Example 3 (Unequal Lengths)

Input:

[1, 2]
[1, 2, 3]

Output:

Hasil: No proceed

Explanation: The arrays have different lengths (2 and 3). The initial validation catches this and immediately returns "No proceed".

Example 4 (Empty Arrays)

Input:

[]
[]

Output:

Hasil: No proceed

Explanation: The condition if len(arr1) == 0: is triggered, preventing errors on empty lists and returning the exact string "No proceed".

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🚀 How to Use

1. Clone this repository (or save the script)

git clone https://github.com/adiaryaz/Day-43-Array-Rotation-Checker.git
cd array-rotation-checker

2. Run the program:

python main.py

Enter your arrays using standard bracket notation (e.g., [1, 2, 3]) when prompted. The program will run continuously until you submit an empty input for the first array to terminate it.