This is an issue with your code. In your code, arr is a global variable, so when the code runs the second test, there are still values from the first test in arr. You must not have been running more than one test locally, otherwise you'd see the same behavior in visual stuido.

in cpp version code works fine locally on my visual studio and gives the right output while when i do test or attempt it gives wrong output on the site

Example Error:
Expected: equal to (1, 999, 999)
Actual: (1, 118, 999)

While it gives (1, 999, 999) on my visual studio
all error like this on the site when i tried it on my visual studio it gives the EXPECTED CORRECTLY!