In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning.

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Counting digits of a decimal number

Is there an algorithm to count digits of a decimal number other than saving it as a string and then looping to find the decimal point and thus count the digits?
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1answer
99 views

What's the algorithm should I use for seeing how well 2 strings match?

Suppose I have 2 strings: string1 = "home/lisa/Music/some_files/01.05 - Garden Ground.mp3" string2 = "Music/Jim Smith/Unknown/(Deluxe Version/Garden Ground).mp3" string4 = "Music/Jim Smith/Unknown/00 ...
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1answer
100 views

More efficient alternative that checks if a list can be made a palindrome

I asked this question on Stackoverflow, but they told me this is the best place to ask. For my algorithms and data structures class, I have to write an algorithm that is more efficient in the worst ...
5
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1answer
426 views

Compute Adjacent Pair

I was given the following problem: Integer V lies strictly between integers U and W if U < V < W or if U > V > W. A non-empty zero-indexed array A consisting of N integers is given. A ...
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1answer
129 views

How to selecting Teams with Minimum Difference between Knowledge Levels

For the below challenge from a programming site, I am bit confused. Problem Statement: A Professor of Physics gave projects to the students of his class. The students have to form a team of two for ...
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1answer
141 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 ...
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1answer
211 views

How to determine whether two trees (not necessarily binary) are isomorphic

Two ordered trees T' and T'' are said to be isomorphic if one of the following holds: ◦ both T' and T'' consist of a single node ◦ both T' and T'' have the same number k of subtrees, and the ith ...
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2answers
205 views

String Searching algorithm

A title for a movie can be ambiguous. (Eg. The Lord of the Rings, Lord of the Rings, Lord of the Rings, The) There exists a database entry that has a list of movie titles mapped to a unique ...
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0answers
57 views

All clustering possibilities for a graph

Is there a known algorithm for finding all clustering possibilities for a directed graph? EDIT: By cluster i mean a weakly connected sub-graph G, so that E(G) > 0. By a clustering possibility I ...
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1answer
211 views

Program to look at the first say 5 characters of a word and return a string if that string is actually the first 5 characters of a word?

For example, say I have a string and it has the letters: RDNAL This is not an actual English word or it doesn't start an actual english word, so the program would skip this string and would avoid ...
2
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1answer
103 views

Need an algorithm to filter this collection format

I'm sorry the title is so vague ... I cannot think how to describe it any better. I have a collection in this format: var myCollection = [{id:"a"}, {id:"b",excludes:["a"]}, {id:"c",excludes:["b"]}]; ...
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2answers
157 views

Line intersection detection algorithm

I'm trying to detect if a line drawn by the user intersects itself. I'm using a line intersection detection algorithm that goes through each waypoint of the line and checks if intersects with any ...
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0answers
237 views

What algorithm is this?

I have some vague recollections from my algorithms courses, but nothing specific comes to mind. let S be a multiset of things we are interested in. As input, we get T, s1, s2, ... sn, all of which ...
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0answers
53 views

python: area mapping using trigonometric circle

I have a car controlled by a raspberry pi, I would like to create maps to each place it visits. The solution I came up with is simple. Lets say you tell the car to go forward and then after 5 minutes ...
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1answer
103 views

Algorithm to 'segment' a number into blocks of n?

I'm not sure how to word the title properly, but the problem goes something like this: I have 5 nodes, and node 0 is the "master". User inputs a number, e.g. 100 to the master. master "splits" the ...
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3answers
289 views

What algorithm can I use to find the biggest subarray within a 2d array with only n different numbers?

Let's say I have a 2d array 100x100 in size, each cell in that array has a number from 1 to 50 randomly. How do I find the biggest subarray in a rectangle size in that array that has only n different ...
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1answer
119 views

dynamic programming with memoization

I’ve a problem with a programming exercise. I hope you can help me. In this exercise I need to find out what the maximum profit is of taking pictures from several items in a park. For taking pictures ...
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2answers
144 views

Estimating run time of algorithm

For instance if i have an algorithm that is O(n2) and it will run for 10 seconds for a problem size of 1000. Now if i were to double the problem size to 2000 i want to know the approximate run time in ...
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1answer
45 views

Matrix distribution to process grid

I need to write a program, which will perform LU-decomposition, etc. The problem is that I don't know about the preferred way to distribute the loaded matrix from the root process to other processes. ...
3
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1answer
127 views

Algorithm to find minimal set

I have a set of sets S and I want to find a minimal set of elements M such that each set in S shares at least one element with M. S = set of sets ∀ f∈S ∃e · e∈f ∧ e∈M For example: S = {{1}, {1, 2, ...
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3answers
353 views

SQL - Algorithm for finding availability of a resource

I'm having trouble creating a mysql compatible algorithm for this. Background App with mysql, perl and JS. It's a booking system where each booking is comprised of a start, end and qty. Start and ...
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0answers
36 views

PSO – how Dimensions are set up?

I am coding a Particle Swarm Optimization in C++. I have been for days trying to understand the theory of how dimensions work in each different problem. In the many examples I have seen, all of them ...
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2answers
125 views

Algorithm Space and Time Complexity with Consideration for I/O (eg cache)

Is there an expression of performance for an algorithm or data structure that attempts to consider cache and other hardware concerns? Context: in my class we're looking at binary trees and it seems ...
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10answers
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Is it reasonable to assume that any physical quantity can be represented by a 64-bit integer without overflow or underflow?

The original binary search algorithm in the JDK used 32-bit integers and had an overflow bug if (low + high) > INT_MAX ...
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2answers
122 views

MJRTY - A Fast Majority Vote Algorithm isn't work [closed]

The MJRTY algorithm sets out to solve the problem of finding the majority element in a stream (an element comprising more than 50% of the stream). Moore proposed to solve this by using only 2 pieces ...
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2answers
6k views

Which way is more efficient for getting the space count?

I have just started reading Cracking the Coding Interview. One of the problems (specifically 1.4) after solving and then looking at the answer made me question the way it is done and decided to post ...
2
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1answer
65 views

timed events to modulation of real-time audio

I am new very to audio programming and am having trouble figuring out the right kind of algorithm for converting control events (e.g. like MIDI) to real-time sound genesis with a buffer. At the ...
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1answer
94 views

Connected components of undirected graph

Suppose I have an undirected graph G with vertices v1...vn and edges. Right now it is in adjacency list representation. For every time moment I have as input some subset of vertices that are "active" ...
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0answers
65 views

A fast algorithm for a simple multi-objective minimization?

I have a set of n (arbitrary) integer numbers S which I want to partition into k subsets S_i each of size n/k (you can assume that k divides n). Let A be the arithmetic mean of elements of the set S. ...
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1answer
80 views

Should changes to FNV-1A's input exhibit the avalanche effect?

This is kind of related to Which hashing algorithm is best for uniqueness and speed?. In that question, the excellently written top answer notes, Randomnessification The other subjective ...
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1answer
190 views

Would adding more digits be a way to scale a order generation service? [closed]

I am working on interview questions from Amazon.com Software Development Engineer Intern Interview Questions. One of the interviewees was asked "give a scalable system design of Amazon.com's order ...
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2answers
153 views

c++11 random: why different range of int and real?

In the c++11, we now have <random> to produce random number. About uniform distributions, we have following int_distribution and double_distribution: uniform_int_distribution-produces integer ...
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2answers
163 views

What is a formal definition for an algorithm step?

Consider the following code to find the K th minimum element of an array: FindKthMin(A[], k) { A = Sort(A); return A[k]; } Could it be an algorithm without specifying the sort details? ...
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296 views

What benefit is there to using recursive binary search over iterative binary search or vice versa?

In a recent assignment for my programming 2 class we tested the efficiency of searches by populating a java ArrayList with 13,040 strings. The sequential search was obviously slower than the binary ...
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0answers
35 views

Finding the largest bundle of flagged points

I am currently working to develop a program that takes in an array of 4 columns and around 200,000 rows. Each column represents x, y, z (coordinates), and a flag denoting whether or not this point is ...
3
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2answers
282 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, ...
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3answers
287 views

Abstraction in algorithms

I asked some questions about algorithms, and some replied they are abstract concepts, however I don't know what abstraction means for algorithms or how it applies. For objects, I know if we remove ...
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1answer
312 views

What is the most efficient / fastest way to keep a list in order?

I implemented Dijkstra's path finding algorithm in JavaScript and a big part of it involves storing the distances to nodes and fetching the smallest. The distances change often and the smallest is ...
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2answers
273 views

Is recursion a declarative approach to solve the problems?

I have noticed many problems in algorithms textbook are solved by recursion (divide and conquer, backtracking,...) As I tried to enhance my skills in writing them, I have noticed, I just need to ...
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66 views

Approaches to get stats like average latency in last N seconds

I am receiving messages with latency information (LI, {date, latency}). For statistical reasons: (I am open to approx. approaches, stats monitor will be updated in 6-60 seconds) I want to monitor ...
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10answers
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Do algorithms depend on computer architectures?

I read somewhere (forgot which book it is) that algorithms are independent of computer architectures. Some even say algorithms are themselves computation (machines?)? On the other hand, books on ...
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2answers
143 views

Why is the “period of a (pseudo)random number generator” important?

I've been trying to understand (pseudo)random number generator code from various sources and the concept of the period continues to elude me. To satisfy the minimum level of understanding, I've tried ...
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1answer
88 views

Algorithm for a fast search

I am looking for an algorithm (pseudocode, R code) for my problem here. This looks like a lot to read but is actually very very easy to read, and I am just trying to be verbose. I have a list (say ...
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2answers
424 views

Number of strings containing a specific substring

I've seen numerous questions (and answers) concerning the number of binary strings (e.g "10010" containing some binary substring (e.g "00"). I'd like to know if there is a way to generalize this: ...
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1answer
308 views

worst case comparisons for special case insertion sort [closed]

Consider an Insertion Sort with a Sentinel on n values, where every value occurs exactly twice in the input (so n must be even). So the best case input for comparisons is when the elements are ...
3
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3answers
304 views

“Read user input”: Could it be a step of an algorithm?

Based on this definition of algorithm from Wikipedia: In mathematics and computer science, an algorithm is a self-contained step-by-step set of operations to be performed. Algorithms exist that ...
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3answers
328 views

C# if statements

I am currently working on a C# checkers game for a university project in programming. But i have came to the point where i need to check whether a piece can be moved, or jump, but i feel like i'm ...
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3answers
189 views

number of strings, when each character must occur even times

I've been bashing my skull at this problem for some time now, and its really starting to frustrate me. The problem is: I have a set of characters, A, B, C, and D. I have to tell in how many ways a ...
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2answers
253 views

Dynamic Programming Problem - To find smallest integer number 'x' which contains only digits 1's and 0's such that x mod n = 0

To design an algorithm that will output the smallest integer number 'x' which contains only digits 1's and 0's such that x mod n = 0 and x > 0..... For example: 2 divides 10 3 divides 111 4 ...
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1answer
58 views

Accuracy proportional to size

I have lists of data I'm trying to organize where the list with the least variation/most precision/closest to the average and most amount of data is most highly rated. Some of the lists are like 2000 ...