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2
votes
1answer
346 views

Failure to understand logic behind dice roll permutation problem

I am having a lot of trouble understanding the logic behind the infamous "Find total ways to achieve given sum with n throws of dice having k faces" question. After extensively searching for ...
-3
votes
1answer
164 views

Is my algorithm for determining whether a ipv4 is public or private correct? [closed]

I have just created a function which checks whether a ipv4 is public or not. I have not heavily tested it yet since it is kind of practically impossible to do so (because I do not know where to start)....
0
votes
1answer
184 views

How to manually model a UML activity Diagram to JSON with Qt C++?

Suppose I have a kind of UML activity diagram with 1-n forks and joins. The assignment of the individual nodes relative to each other is defined by an XML relationship table via UUIDs where each ...
1
vote
1answer
303 views

Binary Search Tree with ID and Duplicate Values

I'm having trouble finding resources for this implementation I'm trying to figure out. I want to save nodes in a binary search tree (self balancing) containing an ID and value struct Score { int ...
7
votes
2answers
505 views

FIFO Min-Max-Heap for Rolling Median

I'm working on a system with hard real-time constraints in c++ and I need a very fast way to calculate the rolling/moving/streaming median of a set of numbers of size N=100 to 300. Normally this size ...
3
votes
5answers
954 views

Fastest way to find all numbers with digits

I have a huge set of over a million numbers of variable lengths. ['773', '2267', '8957251', '170597519', '373590109', '982451707', '999999937', ......] Now given a bunch of digits, say 3 and 7, I ...
3
votes
4answers
98 views

Store csv data as rows or columns in view of the needed processing?

Assume I have some data a csv-Files like ObjectName, PropertyA, PropertyB, PropertyC "Name1", 3, 1, 4 "Name2", 1, 5, 9 "Name3", 2, 6, 5 ... and a typical question I want to answer would be For ...
2
votes
3answers
1k views

Why did the C++ std library have a binary search tree well before a hashmap which is in many ways simpler

Looking at the two data structures and algorithms to handle them, a hashmap is not really any more complicated than a binary search tree and possibly less complicated. And the hashmap has the ...
3
votes
1answer
685 views

C++ generic graph search algorithm with generic data types

I'm trying to implement a generic graph search algorithm in C++, as part of assignment at university, and I encountered problems when trying to implement it, mostly struggling with templates. this is ...
-6
votes
1answer
623 views

What's the best algorithm to assign unique ID/serial numbers to a group of identical objects?

to make this question easier to visualize, let's call this the "chicken mesh problem". Suppose you have a rooster and a number (suppose it is 30) of baby chickens. Goal: Allow the rooster to ...
2
votes
1answer
173 views

Getting the number of bits set in a large integer

I have a large integer N < 10^2500. I need to get the number of bits set in its binary representation. The number is given in base 10 in a file. Here's how I'm doing it right now : I made a class ...
2
votes
1answer
245 views

How can I filter my coordinates system?

Following up with this, I have a bunch of coordinates and I draw them on a bitmap image as a coordinate system. Now, I would like to get rid of all the noise, and filter coordinates to give a "clearer"...
0
votes
2answers
97 views

Getting a stateless time-based index out of overflowing timer

I'm currently working on an Arduino project where I need to keep track of entries for a certain amount of time, in this case, 30 days. Our company will attempt to sell this product to cities and ...
3
votes
1answer
641 views

Pitch/Time Shifting of a PCM byte array

I am searching for a universal algorithm that shifts pitch and time while keeping the sample rate. (I am trying to program a sound generator (sine, triangle...) as an exercise) I just want to squeeze ...
3
votes
1answer
515 views

Potential legal issues with lock-free / wait-free structures / algorithms

While researching the subject matter - lock-free and wait-free data structures - I'm seeing a worrying amount of mention of patents with this area. I've hobby-researched compression algorithms years ...
0
votes
1answer
675 views

How to traverse “linked list” like structure with parallel nodes

I am working on a signal processing project that allows for parallel processing on data streams as well as inputs and outputs to and from multiple endpoints. The signal chain is broken down into "...
3
votes
1answer
632 views

Word ladder efficency problem

I have a problem dealing with word ladders. The problem is: given two words and a dictionary file, find the shortest word ladder between the two words. So if given the words cat and pot: cat -> cot ...
5
votes
1answer
557 views

Algorithm to find span intersections in a sorted set

I have a set of items strictly ordered on time. Each item can either be single (no Next, no Previous) or part of a span (with either 1 or 2 further endpoints). For example in the picture A is part ...
0
votes
3answers
11k views

Bresenham Vs Midpoint Circle drawing algorithm

Can somebody explain the difference between Bresenham and Midpoint Circle drawing algorithms? All I am able to understand is that in both algorithms we compute coordinates of an octant instead of ...
5
votes
2answers
313 views

How to optimize/parallelize the following clustering/joining algorithm:

I have relatively-small algorithm that takes up ~60% of the total run-time of my scientific code (57 lines of 3600), so I would like to find a way to optimize what I'm doing and make the code order-...
-2
votes
3answers
479 views

Link to ISO doc? Complexity of unordered_map operations in C++::stl [closed]

In different forums, I have found the statement that in C++::stl, insert and find for unordered_map have guaranteed amortized time complexity O(1). This puzzles me, and I would like to see the ...
4
votes
1answer
843 views

Optimal fixed-size sequential sorting algorithms

I have been working on sorting algorithms for a few weeks now, but one of my question still hasn't an answer: are there optimal sequential comparison sorts for fixed-size – and random-access – ...
0
votes
1answer
603 views

Best algorithm for “ACM ICPC Team”

I have this problem (complete description): There is a list of persons N and M topics. I have to find out the maximum number of topics a 2-person team can know. And also find out how many teams can ...
3
votes
2answers
466 views

How to iterate through all permutations of valid links between nodes

Imagine a 2D area, with a number (array) of nodes (or points) defined within it, in arbitrary (but known) positions (integer x,y coordinates), like this: From there I want to be able to, ...
2
votes
1answer
719 views

Genetic Algorithm's Tournament Selection limit to be selected

I started working again on a Genetic Algorithm and i'm trying a lot of operators and ways of selection. When I made the Tournament Selection , I noticed that it gets really easy to always get the top ...
4
votes
3answers
9k views

Efficient algorithm to count number of substrings divisible by 3

Given a string of decimal digits, I have to find the number of all substrings divisible by 3 in the range L to R [both inclusive], where L & R are index[1-based] of the specified string string ...
1
vote
2answers
614 views

saving connectivity information in a nodes/edges network

I want to implement the A* algorithm. I have a network with Nodes and Edges, both are classes. Now, I am unsure how to approach the connectivity information. Should a node know which edges depart ...
1
vote
4answers
1k views

How to work around Java's lack of pointers to pointers when working with linked data structures? [closed]

I've learned from a textbook how to implement binary search trees recursively in Java, and am working on implementing them nonrecursively. I've found a simple and elegant way to implement an insert ...
4
votes
1answer
149 views

How to define the motion path of one object on a surface of the other one?

I have an uncommon problem. There are 2 3D objects, which are represented by arrays of vertices and triangles (.stl files). Each of them contains a big enough amount of vertices: 1-10 mln ones. The ...
-2
votes
2answers
510 views

Which algorithm is faster? [closed]

I'm creating a small game, where the computer generate pseudo random number in give range, and the user have to guess it. I also made the option to play computer vs computer. I mean the computer ...
4
votes
1answer
2k views

Dynamic programming in Bin packing

Problem: Given a list L of objects of possible sizes from set S={1,2,4,8} and unlimited supply of bins of sizes 16 each and we have to use minimum possible numbers of bins to pack all objects of L. I ...
0
votes
1answer
2k views

Algorithm to Copy data faster than windows default copy provider

I need an algorithm which can copy data(files/folder) from one place to another, faster than windows default copy/paste option. I'm working in vc++. Is there any algorithm by which I can do copy/paste ...
-1
votes
1answer
483 views

How to solve linear recurrences involving two functions?

Actually I came across a question in Dynamic Programming where we need to find the number of ways to tile a 2 X N area with tiles of given dimensions.. Here is the problem statement Now after a bit ...
0
votes
1answer
170 views

Estimed number of tries

Problem: The Oscar Committee wants to decide which person should get the best actor award among the given N actors.For that they decided to use a random function random_bit() which returns either 0 ...
-1
votes
1answer
733 views

Optimal movie schedule

Let's say Mr. A goes to cinema and he gets a movie schedule. There are N movies on the program today (1 < N < 50) and for every movie the time of the start and the time of the end are given in ...
0
votes
3answers
1k views

Print bottom view of a binary tree

For a binary tree we define horizontal distance as follows: Horizontal distance(hd) of root = 0 If you go left then hd = hd(of its parent)-1, and if you go right then hd = hd(of its ...
4
votes
2answers
948 views

How to find number of points with same minimal distances on matrix

I'm trying to find the number of points in a matrix with the same minimal distances. Start with a MxN matrix, where M and N < 50000. There is given a set of fixed points, with their respective ...
6
votes
3answers
1k views

How to extract the active code path from a complex algorithm

I have been puzzled lately by an intruiging idea. I wonder if there is a (known) method to extract the executed source code from a large complex algorithm. I will try to elaborate this question: ...
1
vote
1answer
300 views

LLVM case: is the success due to the algorithms? [closed]

I'm not sure if this is a subjective question, I hope not but I'm not proficient with LLVM so I'm just wondering: how come it's become so popular and so widespread used in the industry? Were the ...
7
votes
3answers
944 views

Apple eating problem

Player A and Player B play a game. On the middle of the table there is a pot full of N apples of different weights. Player A starts first and choose an apple and start eating it. Losing no time player ...
0
votes
5answers
3k views

Binary Search seems superior, why did the committee of C++ still have Find in the algorithm library?

I wish to search for an integer in a vector of integer. I have two candidates for the job: Binary Search Find It seems that Binary Search is the best candidate for the job as although I have to sort ...
0
votes
0answers
428 views

R* Tree work with dynamic data

I'm searching an algorithm to store my data (which are moving objects' coordinates) and allow me to query objects within a specific radius of a specific point. I came up with R* Tree which is said as ...
2
votes
1answer
580 views

Is there already a “Binder” data-structure?

I was thinking of a data structure that I cannot describe better than with the word "book", or more exactly "binder". I was wondering if this had already been implemented in libraries like Boost or ...
6
votes
1answer
1k views

Using std::sort et al. with user-defined comparison routine

In the evaluator of a custom language, I would like to replace our own sort routines with std::sort or other routines, possibly tbb::parallel_sort. The problem is that we allow users of the language ...
1
vote
4answers
430 views

Application qos involving priority and bandwidth

Our manager wants us to do applicaiton qos which is quite different from the well-known system qos. We have many services of three types, they have priorites, the manager wants to suspend low priority ...
-1
votes
2answers
119 views

Store a tree with near next neighbours

I would to find an efficient structure (speed and volume) to store nodes and their neighbourhood. My input is build out of stings in the following format ./X/Y.log where X ∈ [0,359] and Y &...
8
votes
3answers
474 views

Change of the complexity class through compiler optimization?

I am looking for an example where an algorithm is apparently changing its complexity class due to compiler and/or processor optimization strategies.
1
vote
1answer
1k views

What data structure is suitable for implementing dynamic huffman encoding and decoding on a piece of text?

Some pseudo code or resources will be appreciated.I was thinking if implementing it in form of a BST stored in an array. However,not all operations can be performed easily using this approach. I am ...
35
votes
9answers
8k views

Is the algorithm more important than the programming language?

During the current (2013) Google Code Jam contest, there was a problem that took C++ and Java people 200+ lines of code as compared to Python people that solved the same problem only using 40 lines of ...
1
vote
2answers
4k views

How to find local maxima in matrices?

I need to develop an algorithm for finding all the local maxima in a two-dimensional array: how to search for local maxima in the the most efficient way? Are there algorithms about it? Moreover, the ...