Q. Reverse the order of the elements on a stack S

   (i) by using two additional stacks

(ii) by using one additional queue.

Ans:      Let S be the stack having n number of elements. Now we need to reverse the elements of S (i) using the two additional stack S1 and S2

while not empty (S)

{       C=pop(S);

push(S1,C);

}

While not empty(S1)

{     C=pop(S1);

push(S2,C);

}

While not empty(S3)

{     C=pop(S3);

push(S,C);

}

(ii) using one additional queue Q

while not empty (S)

{       C=pop(S);

enque(Q,C);

}

While not empty(Q)

{     C=deque(Q);

push(S,C);

}