Develop a new algorithm 3waypartition(a, p, r) that takes as input array a and two indices p and r and returns a pair of indices (e, g). 3waypartition should partition the array a around the pivot q=a[r] such that every element of -1)] is strictly smaller than q, every element of a[e..g-1] is equal to q and every element of a[g..r] is strictly greater than q.