A team of biologists keeps information on the weight of n DNA structures in an ordered list L i.e. that position L[i] in the list contains the weight of structure i, where the structures are ordered in ascending order of weight. Biologists want to effectively answer the question, "How many DNA structures exist with a weight between a and b, inclusive?"

Give the pseudocode of a divide-and-conquer algorithm which answers this question. Give and explain the time complexity of this algorithm. You can consider the weights as integers.

Do the trace of the algorithm on the list L  =  [1, 2, 4, 5, 5, 6, 7, 8, 8, 9],

with a = 3 et b = 8.