What does the following algorithm do? Analyze its worst-case running time and express it using "Big-Oh" notation. Algorithm Foo (a,n): Input : two

What does the following algorithm do? Analyze its worst-case running time and express it using "Big-Oh" notation. 

     Algorithm Foo (a,n):

     Input: two integers, a and n

           Output: ?

           k  ß 0

           b  ß 1

           while k < n do

           k  ßk + 1

           b  ß b *a

           return b