For questions about sorting algorithms and their speed and complexity.

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6
votes
2answers
191 views

Efficient algorithm to merge n successive sorted arrays in place

I am developing an in-place sorting algorithm that leaves the array into a state where it is basically a succession of sorted subsequences of any size (most are bigger than log2(size(array))); then it ...
7
votes
6answers
11k views

How do I figure out the minimum number of swaps to sort a list in-place?

In-place sorting is essentially swapping elements without using extra storage, correct? How can I find the minimum number of swaps required for a list? A C D Q R Z E // input | | | > > ...
4
votes
4answers
172 views

Best practice for getting last record inserted in DB

Me and a couple of colleagues are having a discussion regarding the following case: In an OrderStatus table we're keeping track of all the statuses an order goes through in time, including ...
7
votes
3answers
2k views

What's the best way to manage list item sort order with Drag & Drop UI?

I have a list of Students that I should display to user on a web page in tabular format. The items are stored in DB along with SortOrder information. On the web page, user can rearrange the list ...
1
vote
4answers
137 views

Should I be using any algorithm to sort/find items, or use a language's built-in ways?

I'm currently a first semester IT student, and I'm wondering if it's better to write my method to find something e.g. in a C# List, or to use any built in method to do these, such as LINQ or .Find or ...
4
votes
1answer
304 views

Sorting a large number of unknown items with multiple stacks

Here is a problem I'm trying to solve for a personal project. I'm not exactly sure how best to even approach it. Problem: I have a single stack already populated with several thousands of unknown ...
0
votes
2answers
87 views

How to find the kth minimum element in an array

I am looking for an efficient algorithm to find the k'th minimum element in an unsorted array of n elements, where 1 <= k <= n. The obvious thing is to sort the array first, then pick the k'th ...
-4
votes
2answers
776 views

Efficient way to sort large set of numbers

I have to sort a set of 100000 integers as a part of a programming Q. The time limit is pretty restrictive, so I have to use the most time-efficient approach possible. My current code - ...
5
votes
1answer
88 views

Sorting algorithm that can handle some error

Suppose you want to sort your movie collection, from favorite to hated. You apply the rules of some sorting algorithm by asking many questions of the form: "Did I like A or B more?" It's now sorted, ...
5
votes
2answers
114 views

How to store ordered information in a Relational Database

I am trying to understand how to properly store ordered information in a relational database. An example: Say I have a Playlist, consisting of Songs. Inside my Relational Database, I have a table of ...
2
votes
1answer
119 views

How to sort a list containing bounded set of values in linear time when length is unknown?

Given a list of integers whose length is unknown, and each of its elements lies between 1 to 1000, how does one sort this list in linear time?
-2
votes
1answer
70 views

Sorting array according to a formula [closed]

I need to sort the values according to the following problem: For every n, determine the triples (i,j,k) that satisfies i+j+k=n, then sort the triples (for every n) with respect to the value of the ...
3
votes
2answers
78 views

How do I model a sortable resource in sql database? [closed]

I encounter this issue when I create REST API. I cannot tell the exact scenario, but let's say it is for a website that has category and product resources. Each category has many products and both ...
-3
votes
1answer
77 views

complexity of an algorithm, sorting 5% out [duplicate]

I have been asked the following question.. An algorithm considers n elements, sorts 5% of n out, considers the remain elements(95%), sorts 5% of the remain elements, and so on until finally one last ...
3
votes
3answers
101 views

How to model heuristic uncertainty when sorting data?

Sorting algorithms assume you have a defined comparator. For example, if sorting integers A and B, the A > B operation allows you to determine if A should be after or before B. Imagine you want ...
2
votes
4answers
3k views

Applications of heapsort [closed]

Heapsort is a sorting algorithm that has a time complexity of O(nlogn), and performs sorting using O(1) space complexity. However, I know that because it's unstable, it doesn't find many applications ...
4
votes
2answers
97 views

Sort a list while putting together or after?

I have to read through an extremely large amount of network data from various log files, and compile relevant information about that data to perform statistical analysis on it (the top communicators, ...
5
votes
2answers
6k views

How to handle sorting of complex objects?

How would one sort a list of objects that have more than one sortable element? Suppose you have a simple object Car and car is a defined as such: class Car { public String make; public ...
2
votes
1answer
80 views

Why is Python sorted() result like this?

I might be missing something obvious here, but why does Python 2.x sorted() function work like this? In [95]: l = [1, '5', 4, 2, '3', 'b', 'c', '-a'] In [96]: sorted(l) Out[96]: [1, 2, 4, '-a', '3', ...
-1
votes
2answers
114 views

Merging Sorted Lists (with no comparison function)

I have a few lists of items (which will likely but not necessarily have common elements). The lists are known to be sorted, but don't have a comparison function (they were manually put into the system ...
2
votes
4answers
717 views

Tournament bracket method to put distance between teammates

I am using a proper binary tree to simulate a tournament bracket. It's preferred any competitors in the bracket that are teammates don't meet each other until the later rounds. What is an efficient ...
4
votes
1answer
159 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 – ...
5
votes
2answers
5k views

Fast algorithm for finding common elements of two sorted lists

Suppose I have two lists of N 3 by 3 vectors of integers. I need to find a quick way (say of running time at most N^(1+epsilon)) to find the vectors of the first list that have the same 1st ...
-2
votes
7answers
2k views

Which sorting algorithms have a different worst case complexity than their average case? [closed]

I'v been working on sorting for a while now but I can't figure these two questions apart, I'm kind of getting mixed up somewhere ... Somebody help a) Which sorting algorithms have a different worst ...
0
votes
0answers
95 views

Algorithm to maximize pairwise comparisons using transitive property

I'm looking for some direction on building an algorithm that will maximize the number of pairwise comparisons of objects in a set using transitivity. To explain in detail: Suppose there are x ...
0
votes
3answers
222 views

Analysis of insertion sort does not equal O(n^2)?

I'm learning more about algorithms and data structures. According to Wikipedia and other reliable sources, an insertion sort has a worst-case time complexity of O(n2). I'm attempting to measure that ...
1
vote
2answers
225 views

Shuffle/Randomize a collection without knowing the number of items? [closed]

Let's say I have a sequence of items of unknown length, n. I want to randomize the order of this sequence without having to go through the entire sequence. Are there any algorithms that can do this? ...
-2
votes
1answer
48 views

Move file into apropriate directory based upon first letter of second word, followed by the first two letters of the second word with Python [closed]

EDIT: Apparently the below question is too specific. Let me rephrase: I'm looking for a way to fit a letter into a list of specified ranges such that, if given the letter S and the ranges A-F, G-M, ...
0
votes
1answer
196 views

How to sort fractions (small numbers)

We have 100 000 fractions: Let's consider following fractions. p/(2^q) such that 0 <= p,q <= 10 As you can see there are <= 10 * 10 different fractions, but we have 100 000 that we have to ...
4
votes
4answers
467 views

Why are return values from compare functions in many languages defined loosely?

Many languages define that compare functions should return ANY negative value, zero, or ANY positive value. Is there some reason that it shouldn't be clearly defined as -1 0 and 1? Does a wide range ...
1
vote
3answers
506 views

How can I rank teams based off of head to head wins/losses

I'm trying to write an algorithm (specifically in Ruby) that will rank teams based on their record against each other. If a team A and team B have won the same amount of games against each other, then ...
3
votes
1answer
877 views

How can this deterministic linear time selection algorithm be linear?

I'm trying to understand the basic concepts of algorithms through the classes offered at Coursera (in bits and pieces), I came across the deterministic linear time selection algorithm that works as ...
3
votes
2answers
101 views

(Partially) Sorting a lazy-evaluated collection

So I'm trying to implement a lazy-evaluating data type (in PHP, though that shouldn't matter any) where you can queue up actions to take on a set of data. This data can come (theoretically) from any ...
0
votes
1answer
136 views

Is external merge sort a divide-and-conquer algorithm? [closed]

Today I was corrected for mentioning "External Merge Sort" as an example of a divide-and-conquer (D&C) algorithm and after doing a lot of research online and in the most prominent books on ...
6
votes
5answers
513 views

Type of AI to tackle this problem?

I posted this on stackoverflow but want to get your recommendations as well as a user on overflow recommended I post it here. I'm going to say from the beginning that I am not a programmer, I have a ...
0
votes
1answer
573 views

Count Sort Algorithm efficiency

As I read a book about "Algorithm Analysis", I came across count_sort Algorithm. However, I have read elsewhere that "Quick Sort/ Merge Sort" are the best and the most efficient sorting algorithms. I ...
5
votes
1answer
324 views

Kth selection routine - Floyd Algorithm 489

I have recently come across a promising Kth selection routine that reportedly outperforms quickselect the Floyd, Rivest Select routine. This Wikipedia article provides a pseudocode version which I ...
1
vote
2answers
173 views

Heuristic for consistiently ordering points in a a plane

I have rectangular regions in a plane. I want to consistently order them in a human-friendly way that a typical y-x sort won't work for. Basically I want (0,0), (1,0), and (0,1) to sort the same as ...
0
votes
2answers
195 views

Can relational database tables always be topologically sorted by their FK reference relation?

Suppose I have some conceptual, not physical, E-R diagram describing a relational database. I want to sort all the tables in the database using a topological sort, where the partial ordering between ...
0
votes
1answer
159 views

Sorting Sentences by New Words in Each

A very useful learning tool I stumbled across for Chinese was a massive list of sentences that, barring the first 10 or 15, only differed by the ones before by one or two words, or at least as few as ...
6
votes
3answers
411 views

Picking m number in the best possible time

Imagine we want to pick m numbers from n numbers so that the difference of the maximum and minimum of the m numbers be minimum, for example if m = 4 n =6 numbers: 10 12 10 7 5 22 The ...
2
votes
3answers
267 views

fast, say O(log2(N)), sliding median algorithm

So I know how to do a fast O(log2(N)) sliding max or sliding min algorithm. Brookes: "Algorithms for Max and Min Filters with Improved Worst-Case Performance" IEEE TRANSACTIONS ON CIRCUITS AND ...
2
votes
2answers
904 views

About insertion sort and especially why it's said that copy is much faster than swap?

From Lafore's "Data Structures and Algorithms in Java": (about insertion sort (which uses copy + shift instead of swap (used in bubble and selection sort))) However, a copy isn’t as time-consuming ...
0
votes
2answers
291 views

Average number of comparison for sort algorithms

I need to write different sort algorithms such as bubbleSort insertionSort selectionSort quickSort mergeSort And measure how many average comparison does each one for N number (averaging between ...
1
vote
1answer
221 views

How to count sort comparison

When it is said that this sort has M number of comparisons what does it mean? As an example: procedure bubbleSort( A : list of sortable items ) n = length(A) repeat swapped = false ...
1
vote
1answer
104 views

filtering data from db

I've taken over a web application that someone else built. It's a pretty simple application that queries ALL records from a db and displays them in a list. They've also provided a way to 'filter' the ...
18
votes
3answers
2k views

Java and .NET: Why different sorting algorithms are used by default?

Just wondering why Java and .NET Framework uses different sorting algorithm by default. In Java Array.Sort() uses Merge Sort algorithm by default and as Wikipedia.com says: In Java, the ...
1
vote
1answer
9k views

Quicksort and middle pivot

I am having a head ache understanding quicksort with middle pivot. I found lot of explanations about using left most or right most, but not many about a middle one. Can I safely assume these?: If ...
4
votes
3answers
170 views

Algorithm that generates a group of men and women who are each interested in everyone from the other gender

In my dating app, I need to compile lists of men and women where all of the men in the list are potentially interested in all of the women in the list, and vice versa. That is, in a list of 10 men ...
1
vote
5answers
6k views

Is Bubble Sort the slowest sorting algorithm? [closed]

Is bubble sort the least Big-O efficient? If the answer is no, then what is the least efficient sorting algorithm?