1. This problem considers several ways to compute xn for some n0. 1) Write an iterative function power 1 to compute xn for n0. 2) Write a recursive function power 2 to compute xn by using the following recursive formulation: x0=1xn=(xn/2)2ifn>0andniseven;xn=x(xn/2)2ifn>0andnisodd. 2. Write a recursive binarySearchWords function for an array of strings (already sorted), that returns the indexes of all the strings (words) whose first letter is, for example ' L ' or 's'. For example, for anArray = \{"books", "elephant", "Letter", "source", "switch", "tigers" }, the search result should show: indexes found are: {2,3,4}. Notes: You should set the target letter to be a variable, so we can use your function to search strings starting with any given letter withing a-z. 3. Write a main() function that tests all the above functions, with two test cases for each function. You may create a menu of choices for user to choose which function to test