Using the below recursive method and assuming n is the length of the array.

int sum(int[] array, int first, int last)

{

if (first == last)

return array[first];

int mid = (first + last) / 2;

return sum(array, first, mid) + sum(array, mid + 1, last);

}

Modify the recursion tree from the previous problem to show the amount of work on each activation and the row sums.

Determine the initial conditions and recurrence equation.

Determine the critical exponent.

Apply the Little Master Theorem to solve that equation.

Explain whether this algorithm optimal.