Index priority-queue implementation. Implement the basic operations in the index priority-...

Index priority-queue implementation. Implement the basic operations in the index priority-queue API on page 320 by modifying algorithm 2.6 as follows: Change pq[] to hold indices, add an array keys[] to hold the key values, and add an array qp[] that is the inverse of pq[] — qp[i] gives the position of i in pq[] (the index j such that pq[j] is i).Then modify the code in algorithm 2.6 to maintain these data structures. Use the convention that qp[i] = -1 if i is not on the queue, and include a method contains() that tests this condition. You need to modify the helper methods exch() and 1ess() but not sink() or swim().