Understanding the reversal pattern

We can access data items anywhere in sequential data structures like arrays and linked lists either via random access (jumping directly to any index) or traversal (walking through the items one by one). However, inserting and accessing data in a stack is only restricted to one end in the stack giving it its unique LIFO (Last in first out) property.

The reversal technique leverages the LIFO property of a stack to reverse any sequence of data by inserting all the items into the stack and then retrieving them one at a time from the top. This way, the resulting sequence from the retrieved items will be in reverse order. Almost all sequences that can be reversed using a stack can also be reversed using another technique (for example, swapping items from the two ends inward, or using recursion).