Resolved Issue #2939

[avibega23]

1. Input Validation in main() function: Issue: The original code did not check for non-positive values of n (array size). As a result, entering a value of n <= 0 would cause buffer overflow or undefined behavior when the array was accessed.

Change: Added input validation for the array size n to ensure it is positive. If n <= 0, the program prints an error message and terminates gracefully:

if (n <= 0) { std::cerr << "Error: Array size must be a positive integer.\n"; return 1; }

2. Handling Empty Arrays in median_of_medians() function: Issue: In the original code, if the array was empty or the median vector m ended up being empty, the program would try to access m[0], causing a buffer overflow.

Change: Before accessing m[(sz - 1) / 2], a check was added to ensure that the median vector m is not empty. If the vector is empty, an error message is printed, and the program exits:

if (m.empty()) { std::cerr << "Error: Median vector is empty.\n"; exit(1); }

3. Graceful Error Handling for Invalid Inputs: Issue: The code previously did not handle invalid inputs properly, and it would crash with a segmentation fault when invalid input was given.

Change: Instead of continuing with invalid or empty inputs, the program now handles such inputs gracefully by printing error messages and terminating cleanly, thus preventing crashes and undefined behavior.

Example: If n <= 0 is entered, the program prints:

"Error: Array size must be a positive integer."

4. Edge Case Handling in Test Cases: Issue: The original test cases did not cover edge cases like empty arrays or non-positive sizes.

Change: Though not explicitly mentioned in the test section, handling of invalid inputs was prioritized in the main function, ensuring no test cases would be executed for invalid inputs.