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Questions tagged [c++]

Programming questions are off-topic here. Do not ask questions about how to write code in C++. However, conceptual questions about computer science are more appropriate. See our help center for the scope of this site.

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5
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1answer
604 views

Where are C++ templates inside of the lambda cube?

C++ templates have type variables and can express lambdas, so they must have System F embedded. But is that exactly where they are located in the lambda cube? Can C++ templates produce new types or ...
4
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1answer
125 views

Why are struct and class essentially the same in C++?

struct and class in C++ are nearly identical (as covered for example here). But why is this so? What did happen when C++ was ...
4
votes
1answer
99 views

Linked list: advantages of preventing movement of nodes and invalidating iterators on add/remove

C++ and Java include native classes for linked lists, C++ std::list and Java LinkedList For C++ std::list, nodes can be "moved" within a list, or from list to list (if the lists are compatible), via ...
2
votes
1answer
52 views

numerically stable log1pexp calculation

What are good approximations for computing log1pexp for single precision and double precision floating point numbers? Note: ...
2
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0answers
65 views

Implementing a linear programming feasibility test in 3D

I have a little problem which requires determining if a system of linear inequalities in 3D is infeasible. The constraints (or oriented planes) are added one by one, so there is an opportunity to stop ...
1
vote
2answers
101 views

How do compilers implement symbolic (rather than textual) insertion?

From a programming language designer's point of view, how is "symbolic" insertion implemented as opposed to "textual" insertion using pre-processor macros? I understand the basics of how "textual" ...
1
vote
1answer
98 views

Complete the following table by specifying the scope of each declaration

I'm having a hard time understanding this question. Can each declaration have more than one scope or can a declaration have more than one scope? If it's the later it would be: Declaration ...
1
vote
1answer
136 views

Why isn't deque implemented as a dynamic array?

We know that std::vector in C++ is implemented as a dynamic array with specific pattern of reallocation (multiplying capacity by a constant), which allows it to ...
1
vote
2answers
53 views

Compare each array $i$ member to all array $j$ member where $(i > j)$ , in time less than $O(n^2)$

I am new to algorithms so sorry to ask simple question I am working on a problem which is about array of integers, my solution is right but not good enough, because I have time exceeded exception on ...
1
vote
1answer
295 views

Find maximum non contiguous subarray that respect a specific rule [closed]

Given these two arrays: [5, 3, 4, 1, 2] [1, 3, 2, 4, 5] Find the maximum subsequence in both arrays that the index of the elements are in a crescent order: ...
1
vote
0answers
29 views

How to justify using available code (in different language) for comparing algorithms [closed]

I have proposed an algorithm for a scheduling problem in a submitting paper. In the revision, the reviewer asked us to compare with another algorithm in the literature. Our algorithm is in MATLAB, and ...
1
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0answers
36 views

How does C++'s type checking work when passing overloaded or templated functions as parameter

As I understand, C++ in general features 'one-way' type checking. That is checking the sub-expressions and get their types, and see if the types so far satisfy the constraints imposed by the current ...
1
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0answers
27 views

Summary of types of equivalence and equality in type theory, with notations and examples

Coming from non-computer science background, I am trying to understand the different types of equivalence and equality usually used in type theory. Ideally, I am looking for clear definitions and ...
1
vote
0answers
62 views

Generate an AST from an indefinite grammar and logic

As said in the title, I have to generate an AST from a grammar and logic (or a"syntax" if you prefer). This grammar and syntax are both indefinite in the program, meaning that it is the user (a ...
1
vote
0answers
1k views

To find median of k sorted arrays of n elements each in less than O(n*k*log(k))

How to find median of k sorted arrays each of length n? Note that total elements would be n*k. I know it can be done in O(n*k*log(k)) using merge technique. I am looking for a better time efficient ...
1
vote
1answer
75 views

Print maximum frequency number in an array(with slight modification)

There is an integer array and 2 variables Q and M.The output required is the number which has the maximum frequency in the array, but the catch is that each number in the array can be increased/...
0
votes
1answer
167 views

Bytes from integer using bitwise operators

So I am extremely confused with using bitwise shifts used to extract the bytes from an integer. I find that if I do something like this... ...
0
votes
1answer
97 views

How to count number of 1s of the first k positions in a bitset (bitmap)?

Input: Given a bitset $b$, which is is an array of 0s and 1s, of length $L$, and a positive integer $k$. Output: the total number of 1s in the first $k$ position of $b$. Obviously it can be done in $...
0
votes
1answer
402 views

Find Length of longest substring with all 1's in a binary string with k queries

Given a string of size n consisting of 0s and/or 1s.you have to perform k queries and there are two types of queries possible. "1"(without quotes): Print length of the longest substring with all '1'. ...
0
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0answers
15 views

Help me explain finding the max in a forward list using recursion C++ [on hold]

So my professor created this code and I don’t fully understand it so I would like an explanation if possible of what exactly is going on. I specifically don’t understand the difference of ...
0
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0answers
11 views

Compiler Shows: Abort Called [migrated]

When does a C++ compiler give a this message : "terminate called after throwing an instance of 'std::out_of_range'"? I was trying this problem a website. I wrote an algorithm but the code won't ...
0
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0answers
64 views

Given n strings, how to output their order after k phases of the radix sort (huge constraints)?

Disclaimer This is not from an ongoing contest, this is from my course of ITMO on edx.org, which is a paid code so I cannot give you a direct link to the course. Problem You are given $\...
0
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1answer
46 views

What operation is the algorithm performing? [closed]

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-1
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2answers
41 views

Find first occurence of multiple tokens using C++ [closed]

I am using C++03. I have a stream of chars and I need to find the first token from a group of tokens. That is, I need to find the lowest indexed match. Specifically, the stream is just an char array, ...
-1
votes
1answer
39 views

How is ReLU used in machine learning functions

I've seen how sigmoid would be used in machine learning sigmoid(dot(activations, weights)-bias) like this ^ but sigmoid makes sure your values are between 0 and ...
-2
votes
1answer
61 views

Halting problem in C++

The halting problem relies on the fluidity of Turing machines. That is, a string can represent a machine. Can you do the same for C++ on a modern computer? Let's see my first attempt. Let ...