Stack + Queue + Priority queue
STACK //while pushing top++ and while pop top-- in full stack TOP=Max-1 and empty stack ->top = -1 Stack is full and we are pushing => overflow Stack is empty and we are popping => underflow QUEUE empty queue -> front = - 1 and rear = - 1 if inserted ,i.e., enqueue => rear++ if deleted ,i.e., dequeue => front++ {NOTE:- front is index before first element} eg .- _523 =>front is 0 bcz 1st element '5' is at index 1 ...