Please show work

For the piecewise function below draw the box trace diagram and answer the related questions. 0 a (n, k) = 1 a(n-1, k-1) +(n-1, k) otherwise (a) Draw a box trace diagram showing the evaluation of a(4,2). What is the value of (4,2)? How many calls are made to a, including the initial call, when evaluating a(4,2)? List the calls in the order that they are made. [15 points) b) Suppose '(n, k), a version of the function that uses memoization, is implemented. Draw a box trace diagram showing the evaluation of a'(4,2). How many calls are made to a', including the initial call, while evaluating a' (4,2)? List the calls in the order that they are made. [10 points