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Reverse stack using two stacks

reverse stack using two stacks

Array a[n] consists of elements from a[0] to a[n-1]. Stack is a data structure in which an element that pushed last can be the first element to be popped.

So, In this program we pushed all character of a string a stack and then we popped it. In this program we are taking stack array as int data type. In this we are taking the array stack as integer data type but it must be character datatype.

For Stack data structure, by default top variable always point to last pushed value in stack. Google Add. Like us on FaceBook Programming Videos. In this question, A string is input by a user and our program will reverse a string using a Stack. Stack Data Structure Stack is an abstract data type in which push insertion and pop deletion operations can be done at one end.

Sort a Stack using another stack

Some important articles regarding Stack data structure and it's implementation. By Programming Tutorial. Unknown October 8, at AM. Programming Tutorial October 9, at PM. Unknown March 7, at PM.

Unknown September 29, at AM. Unknown July 8, at AM. Sushma January 19, at AM. Unknown September 12, at AM. Unknown February 27, at PM.

Unknown October 4, at AM. Programming Tutorial October 4, at AM. Unknown October 9, at AM. Unknown October 6, at AM. Unknown January 6, at AM. Newer Post Older Post Home.

Subscribe to: Post Comments Atom.Reverse a stack without using extra stack i. Kind of stupid question. In recursion you are using program stack to hold the popped values. Without recursion you can achieve the same using another stack. One point friends I dont think this is a stupid question. When the interviewer asks for a recursive solution, it does not mean that it is the best solution in terms of time and space.

The purpose of the question is to understand the candidates knowledge of recursion and how well he can think recursively. And yes. I guess you need three of them. Isn't it a tower's of hanoi kind of problem? Let me know. With O n extra space it is trivial. Without extra space, you need recursion to hold values. You can ask the interviewer that if I have source code of given stack, if I have the information on how the stack is implemented, then reverse that internal data structure of stack for example, array and linked lists can be reversed using constant extra space.

Finding the internal structure and using it is much more easier and correct to achieve the desired stack reversal in O 1 rather than using double recursion which uses an internal function stack anyway.

First, think about how to add a data to the bottom of the a stack, which requirement a recursive function. If you can sort out the 1st question, then it is straight forward to use another recursive function to revert a stack. I think this would be implementation depended Hi, I am commenting on a very old thread.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I can only use poppushand reverseStackno additional functions such as insertAtBottom which I've found while search stackoverflow and the web.

Learn more. Recursively reverse a stack Ask Question. Asked 5 years ago.

reverse stack using two stacks

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Reverse a stack using recursion

John Costanzo John Costanzo 11 1 1 silver badge 4 4 bronze badges. Are you allowed to push the items onto a second stack and then swap the stacks at the end? Active Oldest Votes.

Chintan Ghate Chintan Ghate 1 1 silver badge 8 8 bronze badges. It skips the use of top method call per element in the stack.

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home?The problem is opposite of this post. We are given a Queue data structure that supports standard operations like enqueue and dequeue. We need to implement a Stack data structure using only instances of Queue and queue operations allowed on the instances. A stack can be implemented using two queues.

Method 2 By making pop operation costly In push operation, the new element is always enqueued to q1. In pop operation, if q2 is empty then all the elements except the last, are moved to q2. Finally the last element is dequeued from q1 and returned. References: Implement Stack using Two Queues. This article is compiled by Sumit Jain and reviewed by GeeksforGeeks team.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment? Please use ide. Stack s. Program to implement a stack using.

Two inbuilt queues. To maintain current number. Push x first in empty q2. Push all the remaining. This code is contributed by PranchalK. Enqueue x. Enqueue q1. Peek. Dequeue. WriteLine s. Enqueue res.

reverse stack using two stacks

Push 1. Top. Push 7. Push 9. Pop .Reverse a Stack without using recursion and extra space. Even the functional Stack is not allowed. Reverse a Stack using Recursion. The above solution requires O n extra space. We can reverse a string in O 1 time if we internally represent the stack as a linked list.

Reverse a stack would require a reversing a linked list which can be done with O n time and O 1 extra space. Note that push and pop operations still take O 1 time. This article is contributed by Niharika Sahai. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.

See your article appearing on the GeeksforGeeks main page and help other Geeks. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment? Please use ide. StackNode int data. StackNode next. StackNode top. StackNode prev, cur, succ. Write s. WriteLine. WriteLine "Original Stack". WriteLine "Reversed Stack". Recommended Posts: Clone a stack without extra space Find maximum in a stack in O 1 time and O 1 extra space Print reverse of a Linked List without extra space and modifications Design a stack that supports getMin in O 1 time and O 1 extra space Stack Set 3 Reverse a string using stack Find pair for given sum in a sorted singly linked without extra space Reverse the Sentence using Stack Reverse a number using stack Reverse a stack using recursion Length of longest palindrome list in a linked list using O 1 extra space Print Reverse a linked list using Stack Program to reverse a linked list using Stack Design a stack to retrieve original elements and return the minimum element in O 1 time and O 1 space Design and Implement Special Stack Data Structure Added Space Optimized Version Infix to Postfix using different Precedence Values for In-Stack and Out-Stack.

Improved By : lakshayguptaandrew Load Comments.The problem is opposite of this post. We are given a stack data structure with push and pop operations, the task is to implement a queue using instances of stack data structure and operations on them. A queue can be implemented using two stacks.

Let queue to be implemented be q and stacks used to implement q be stack1 and stack2. Method 1 By making enQueue operation costly This method makes sure that oldest entered element is always at the top of stack 1, so that deQueue operation just pops from stack1.

To put the element at top of stack1, stack2 is used. Method 2 By making deQueue operation costly In this method, in en-queue operation, the new element is entered at the top of stack1. In de-queue operation, if stack2 is empty then all the elements are moved to stack2 and finally top of stack2 is returned. Method 2 is definitely better than method 1. Method 1 moves all the elements twice in enQueue operation, while method 2 in deQueue operation moves the elements once and moves elements only if stack2 empty.

So, the amortized complexity of the dequeue operation becomes. Implementation of method Queue can also be implemented using one user stack and one Function Call Stack. Below is modified Method 2 where recursion or Function Call Stack is used to implement queue using only one user defined stack. The step 3 makes sure that the last popped item is always returned and since the recursion stops when there is only one item in stack1 step 2we get the last element of stack1 in deQueue and all other items are pushed back in step.

Writing code in comment? Please use ide. Queue q. Python3 program to implement Queue using. Move all elements from s1 to s2. Push item into self. Push everything back to s1. Dequeue an item from the queue. Return top of self. This code is contributed by PranchalK. Push s1. Pop. Push x. Push s2.Post a Comment You are most welcome for making comments here. I will consider your view and will reply you soon. Online home of Computer Languages and Programming.

Your Learning Road Goes Ahead Saturday, November 5, Reverse a Stack using two stacks in C language. Posted in: "reverse stack"helping stack.

Lec 42 Implementing Stack using Queues

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reverse stack using two stacks