What does the [L..R] part mean? How do I determine the run times? Please no complex answers or any complex coding samples.

An outline of the function is given below. int funl (int A[L..R]) { if (L R) return (A[L]); M = (L + R) / 2; return MAX{ fun1 (A[L..M]), fun1 (A[M+1..R]) }; } Write a C++ program to implement the above function. Then determine the running times of the program for different values of N and plot it. Verify that it matches with the theoretical complexity