How can I remove an item from a stack which is not at the top?


#1

Question

In this exercise, the three listed stack operations are push, pop, and peek. Is it possible to remove an item from the stack which is not the top item?

Answer

Removing an item that is not at the top of the stack can be done using the available stack operations by using a second temporary stack to hold values. As you are examing the first stack for the item to remove, you pop items from the first stack and push it onto the second. Once the item has been found and removed in the first stack, you reverse the process by popping items from the second stack and pushing them back onto the first stack. This allows you to remove an item from within a stack without breaking the expected behavior of the stack structure.