4. ( 25 points) Consider bubble sort which works by repeatedly swapping adjacent elements that are out of order. - Write a pseudo code for this algorithm. - What loop invariant does the inner loop of this algorithm maintain? - Give the best case, average case and worst case running times in -notation. - Construct the decision tree for this sorting algorithm with three inputs a1,a2,a3. 4. (25 points) For the activity selection ponlem enth the follons start and fieut apply greedy stzategy to consmisl as vprithal selection