Questions tagged [stacks]

A stack is a Last In First Out (LIFO) data structure. A common use of stacks is to store subroutine arguments and return addresses.

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Formal semantics of a mutable/imperative stack

When introducing formal semantics for data structures, immutable stacks are a nice simple example : $\mathit{is\_empty}(\mathit{create()})=\mathrm{True}$ $\mathit{is\_empty}(\mathit{push}(e, s))=\...
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kPDA handling multiple epsilon transtions

I'm assigned to build a kPDA with 2 stacks that handles {w#w, where w is a string of (0,1)*}. I understand the # delineates the two strings, but I'm unsure of the logic when popping off stacks with ...
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stacks in tree constructions

There are two nice tree constructions, that use a stack in a similar manner: Construct a binary search tree from a pre-order traversal (e.g. see http://www.geeksforgeeks.org/construct-bst-from-given-...
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Is there a known way to make an efficient, compact, and fully persistent stack or queue?

In the world of mutable/ephemeral data structures and imperative programming languages, one of the classic ways to implement a stack or queue is to use array doubling: use mutation to fill up or empty ...
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Direct addressing on a huge array

A Question from CLRS book: (CLRS 11.1-4) We wish to implement a dictionary by using direct addressing on a huge array. At the start, the array entries may contain garbage, and initializing the ...
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What is the algorithm to determine valid push and pop sequences for stack when repetition of numbers are allowed?

Unlike traditional problems dealing with push and pop sequences of distinct numbers, I would like to know the procedure to determine the validity of the stack operations for sequences of non-distinct ...
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29 views

Same computation order using postfix notation?

I'm trying to understand arithmetic using stacks. Specifically converting infix notation to postfix notation. My question is how you convert an expression like: 1 + (2 + 3) + (4 + 5) that computes in ...
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21 views

When does kernel accessing virtual memory cause problems

I'm working with the CPU Pintos and have a question that is: In which situations can the kernel accessing the data in virtual memory via a pointer lead to problems? And how do you avoid them? I know ...
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Manage nested recursions in the design of a concatenative language interpreter

I'm in the designing of an interpreter for a stack based concatenative language, and I'm currently stuck with a problem about recursion of some of my concatenative program to calculate factorial: <...
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28 views

Manage event programming under a stack-oriented language

I wonder how events, or more broadly reactive programming, could be managed in a simple stack-oriented language. For example, let's imagine a context where there is a button that displays a small ...
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Is it still called “recursion” when you're using call-stack as a stack?

The most obvious way to solve a problem of balancing parentheses, like https://leetcode.com/problems/valid-parentheses/, is through a stack (a last-in-first-out (LIFO) datastructure). However, if you ...
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143 views

Multiple post-fix expressions for an in-fix expression

Today I was learning to convert post-fix expressions to in-fix expressions and vice versa. What I want to know is whether a post-fix expression can have more than one infix representations. For ...
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stack vs queue efficiency

Is there any literature / research on the average size efficiency of stacks vs queues? I asked because I was recently working on a problem where, if using a queue, the size quickly blew up and the ...
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Understanding time complexity of dynamic array implementation of stack

let me tell you first what is written in the book I am following. If the array is full,create a new array of twice the size, and copy items. At n=1,we do 1 copy operation,at n=2,we do 2 copy ...
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Implement heap using stack data structure

I want to implement a heap using the stack data structure. I have searched a lot on the internet. But I do not get any clue how to implement it. Can you please help me to implement a heap using the ...
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Collecting and combining data from iterative DFS on read-only trees

I am iterating over a tree through an API. This API provides a list of nodes sorted in post order DFS. I need to gather data for each node in the tree, combine that data with the parent's data (...