a) Describe the algorithm which in 6 comparisons correctly finds median (the third) out of five unequal numbers (rocks) A1, A2, A3, A4, A5

b) Describe the algorithm which in 3 comparisons with lever scales finds among 12 coins a single false coin (which is different from standard in weight) and also finds if the false coin is lighter or heavier than a standard

c) Given two numbers X and Y in the computer memory. Exchange/swap these two units of memory, i.e., get Y and X without using any extra memory. (e.g. you can use X = X + Y, but you cannot use Z = X since Z is forbidden)