How to Indetify Stack:
if j in inner loop depend on i .
such as loop from j = i to n  or j to i etc.
then 100% stack is requires for better solution

Monotonic Stack :
1. Find Next Greater Element
2. Find Next Smaller Element
3. Find Previous Greater Element
4. Find Previous Smaller Element
 IN layman terms : nearest greater element on left or right side of an element in an array.

 QUEUE:
In case of Circular Queue:
increment = ( + 1 ) % capacity
decrement = ( - 1 + capacity ) % capacity