{"id":13588,"date":"2023-02-22T12:35:02","date_gmt":"2023-02-22T12:35:02","guid":{"rendered":"https:\/\/www.prepbytes.com\/blog\/?p=13588"},"modified":"2023-10-18T06:08:01","modified_gmt":"2023-10-18T06:08:01","slug":"reverse-a-stack-using-recursion","status":"publish","type":"post","link":"https:\/\/prepbytes.com\/blog\/reverse-a-stack-using-recursion\/","title":{"rendered":"Reverse A Stack Using Recursion"},"content":{"rendered":"

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In this tutorial, we will delve into a well-known problem in data structures: "Reversing a Stack Using Recursion." If you have a good understanding of both stacks and recursion, tackling this task won’t be overly complex. Rest assured, we’ll cover the essentials, including explanations of what a stack is, the concept of recursion, and the step-by-step process of reversing a stack using recursive techniques. Let’s start by exploring the definition of a stack.<\/p>\n

What is a Stack?<\/h2>\n

The Stack, a linear data structure, operates based on the Last-In-First-Out (LIFO) principle. This structure possesses a singular end, known as the rear end, and a lone pointer referred to as the top pointer, which indicates the highest element within the stack. Whenever an element is introduced into the stack, it is consistently placed atop the stack, and the only operation permissible for removal is from the stack’s uppermost part. In simpler terms, a stack serves as a receptacle permitting the addition and elimination of elements solely from one extremity, which is the uppermost section of the stack.<\/p>\n

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The terms "Push operation"<\/strong> and "Pop operation"<\/strong> refer to the operations used for addition and removal of the elements from the stack, respectively.<\/p>\n

Let\u2019s see how we can \u201creverse a stack using recursion\u201d.<\/p>\n

How To Reverse a Stack Using Recursion<\/h2>\n

The term "recursive solution" is used in the problem name itself.<\/p>\n

It’s important to note that a standard stack primarily involves two key operations at its top: the "push" and "pop" operations. Consequently, when the objective is to reverse a stack, the approach involves systematically performing "pop" operations on each element and transferring them one by one to a separate auxiliary stack. Ultimately, this auxiliary stack will contain the same elements as the original stack but in the reverse order.<\/p>\n

Recursion can be used instead of an additional stack as it is not what we are after. A recursive function also functions similarly to a stack. Therefore, what we will do is build a recursive function that pops every item from the stack and saves it in the function call stack. The new item kept in the call stack is pushed to the bottom of the input stack when the input stack is empty.<\/p>\n

In order to return to the previous state of recursion, we push the stored element in each recursion stack at the bottom of the input stack. In brief, we remove the top element of the input stack and store it in the recursion stack until the stack becomes empty.<\/p>\n

Logic To Reverse Stack Using Recursion<\/h3>\n

The goal of the solution is to keep every value in the Function Call Stack until it becomes empty . Place each held element one by one to the bottom of the stack after it is completely full.<\/p>\n

Dry Run<\/h3>\n

The example of the above strategy may be seen below.<\/p>\n

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  • \n

    Let given stack be<\/p>\n

    \"\"<\/p>\n<\/li>\n

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    4 will be supplied to the function insert at the bottom after all calls to reverse, and when the stack is empty, 4 will then be pushed to the stack.<\/p>\n

    \"\"<\/p>\n<\/li>\n

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    The function insert at bottom will then receive 3 and check to see if the stack is empty or not before inserting 3 and pushing the other components back.<\/p>\n

    \"\"<\/p>\n<\/li>\n

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    The function insert at bottom will then receive 2 and check to see if the stack is empty or not before inserting 2 and pushing back the other elements if necessary.<\/p>\n

    \"\"<\/p>\n<\/li>\n

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    The function insert at bottom will then receive 1 and check to see if the stack is empty or not before inserting 1 and pushing back the other components if necessary.<\/p>\n

    \"\"<\/p>\n<\/li>\n<\/ul>\n

    Following are the steps mentioned below to implement reverse a stack using recursion:<\/strong><\/p>\n

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    1. Make a stack and place all the elements inside of it.<\/li>\n
    2. Call the function reverse() to remove every piece from the stack, then feed the removed element to the insert at bottom() function.<\/li>\n
    3. When the function insert at bottom() is invoked, the provided element is inserted at the bottom of the stack.<\/li>\n
    4. Print The Stack Elements.<\/li>\n<\/ol>\n

      Code Implementation<\/strong><\/p>\n\t\t\t\t\t\t