An approximate value of pi can be calculated using the series given below:
pi = 4 [ 1 - 1/3 + 1/5 - 1/7 + 1/9 ... + ((-1)^n) / (2n + 1) ]
Write a C++ program to calculate the approximate value of pi using this series. The program takes an input n that determines the number of terms in the approximation of the value of pi and outputs the approximation. Include a loop that allows the user to repeat this calculation for new values n until the user says she or he wants to end the program.