PHP 7 Data Structures and Algorithms

Understanding stack

The stack is a linear data structure that follows the Last-In, First-Out (LIFO) principle. This means that there is only one end for the stack, which is used to add items and remove items from the structure. The addition of new items in the stack is known as push, and push whilst removing an item is known as pop. Since we only have one end to operate, we are always going to push an item at that end, and when we pop, the last item from that end will be popped up. The top most elements in the stack that are also at the very beginning of the stack end are known as the top. If we consider the following image, we can see that after each pop and push operation, the top changes. Also, we are performing the operation at the top ...