Exercise 3: Find a theta notation for the best-case time required by the following algorithm: is_key(s, n, key) { for i = 1 ton - 1 for j=i+1 to n if (si + sj=key) return 0 else return 1 Exercise 4: Trace the algorithm of the Insertion Sort for the input Algorithm: the insertion sort Input: s, n Output: s (sorted) insertion_sort(s, n) { for i = 2 ton { 40 18 134 60 val=si // save si so it can be inserted into the correct place j-i-1 // if val < < sj, move sj right to make room for si while (j1A val