Complexity is the analysis of how the time and space requirements of an algorithm vary according to the size of the input. Use this tag for reviews where the "Big O" is a concern.
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Suffix tree code
I am always having confusion when it comes to run time complexity of an algorithm. I wrote this code for suffix array, I am not sure of the run time complexity of ...
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1answer
86 views
Iterative solution for generating all permutations of a string
I know the runtime for generating all permutations is supposed to be \$O(n!)\$. I'm not sure if the code I wrote for it runs in \$O(n!)\$ though. I'm having trouble analyzing its runtime.
The ...
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2answers
81 views
Function to check truth value of a specific statement
I want to check the truth of A + B - (A & B) == A | B for N-bit numbers. For example, here's a "truth" table for 2-bit numbers. (I know I'm taking liberty with ...
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3answers
392 views
Algorithm to compute the n-th derivative of a polynomial in Python
As a personal exercise, I'm trying to write an algorithm to compute the n-th derivative of an ordered, simplified polynomial (i.e., all like terms have been combined). The polynomial is passed as an ...
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3answers
257 views
Finding Pythagorean triplet in array
We have an integer array as:
private int[] arr = {1, 3, 5, 14, 18, 29, 78};
We have a function which takes three inputs of the array and checks whether:
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2answers
70 views
TopCoder problem “Substitute” - SRM 160 (Division II Level One)
I have solved the problem "Substitute" at Topcoder.
A simple, easy to remember system for encoding integer amounts can be very useful. For example, dealers at flea markets put the information ...
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0answers
45 views
Improving time efficiency of finding maximum area rectangles in a histogram
Here's my solution but I am looking for ways to improve the time complexity of solution. Also this question is categorized as being solved by stack so I would like to know how to approach it using ...
3
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1answer
67 views
Faster palindrome checker in Java
I wonder if there could be a faster palindrome checker in Java. The best one I have is O(n/2) which is O(n) eventually:
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2answers
117 views
Min sub array size with a given sum
How can the time complexity of the following code be improved (assuming it's \$O(N^2)\$)? What about style and patterns?
This code is trying to find the minimum subarray size that adds up to given sum ...
3
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1answer
76 views
Finding the maximum distance from the starting node
I've tried everything to make my program faster but with 250 nodes my code takes around 9 seconds to print the result, and with 5000 nodes it took around 260 seconds.
Is there a way to make my ...
3
votes
1answer
39 views
Creating List of String elements that occur a certain amount of times using only the List ADT
I am tasked with creating a list with no duplicates of all String elements, in this case first names, of an ArrayList. The method is passed a threshold, and the ...
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2answers
46 views
Given a set of random strings, write a function that returns a set that groups all the anagrams together in objective-c
I would like to get feedback on the solution and a question regarding Big O.
I am first converting each character in the string into the array and that would be O(n) then i am sorting the array O(n ...
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6answers
381 views
Find maximum difference between values in an array
My task is to use the following pseudocode and improve it (make it run faster). Also I have to analyze the runtime of the given pseudocode and of my new code that i improved.
What does this algorithm ...
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2answers
89 views
Summing all keys in the leaves of a tree
My program takes 35 sec to run example 2. How can I make my program faster?
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1answer
70 views
Reverse a string [closed]
I use this for reversing a string, but it has O(n) :
reverse(y.begin(),y.end());
How can I reverse a string in O(n/2) ?
4
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1answer
76 views
Local variable lookup table
I'm currently in the process of writing my own programming language and the Virtual Machine for the language is responsible for handing all of the local variable scopes.
I need to support the ...
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2answers
500 views
JavaScript function to convert decimal number to binary
I was recently asked this in an interview for a front-end position and I came up with something like this which seems to work but is clunky. (Number.toString() was ...
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1answer
55 views
Return Object[] while connecting to DB once
I have written this code according to my requirements. But after finishing the code, it looks like there are too many loops. I have reduced it as much as I can. Can you find any improvements that I ...
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0answers
89 views
ACM-ICPC HackerRank challenge in C++
I was doing a programming question in C++ at HackerRank. Given a set of up to 500 bitstrings, each up to 500 bits long, the task is to find the pair a and b such that the bitwise OR contains the most ...
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1answer
44 views
Sum to zero of all triples in a list - n^2 running time
As part of an interview, I had to submit a code sample to solve the classical "triples sum to 0" problem. The reviewer said the algorithm needed to be in n2 time, and I was later informed that the ...
4
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1answer
255 views
Find given number by summing up integers from 2 sorted arrays
I am working on an algorithm question in which I need to find out pair of number out of 2 sorted arrays which sum up to the given number. I need to print out the indexes of those pairs rather than ...
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2answers
220 views
Sort a stack of numbers in ascending order only using push
I have a stack of numbers ranging from 1 to 1 million representing a pile of numbered DVDs. Given the stack in random order I am to sort the stack by only taking an element from the stack and push it ...
2
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1answer
537 views
Finding the sum closest to a target number
Wallace the Weightlifting Walrus is training for a contest where it will have to lift 1000 kg. Wallace has some weight plates lying around, possibly of different weights, and its goal is to add some ...
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2answers
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Sorting a Stack in ascending order
Here's my implementation of sorting a stack in ascending order. The problem statement is as follows :
Write a program to sort a stack in ascending order (with biggest items on top).
You may use ...
4
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1answer
59 views
Worst case runtime analysis of a string partitioning algorithm
Give all the partitionings of a string s such that every substring of the partition is a
palindrome
What is the time complexity of this solution? And, how can I improve my code overall?
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0answers
38 views
Byzantine payment processing code
I've been working on a large Ruby on Rails application for several years. We inherited it and refactored and upgraded it, but there are some sections that have not been touched in at least 5 years (...
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2answers
128 views
Does my Linklist implementation have memory leaks?
Are there any memory leaks in this linklist implementation.Also is the implementation correct?Can the time complexity be optimized?
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2answers
212 views
Improving the time complexity of my back pack algorithm
Is there anyone who can help me improve the time complexity of this backpack algorithm, for which I already use sliding array to improve the space complexity.
The problem is as follows:
Given <...
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3answers
157 views
Simple 1-dimensional labyrinth
I am training a colleague who is familiar with Python but has a limited knowledge of C# and complexity. I thought the following problem could be a good start.
You are in a desert, there is a (...
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0answers
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Time Complexity Analysis,Linear Sliding Window Algorithm Fails in SPOJ Aliens in a Train?
I need to find the largest interval with Value Less than a Limit Lt.
The Data is as Follows
For Every Test Case T
Number of elements N , limit Lt
N number of elements data
I wrote the ...
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3answers
147 views
Long arithmetic addition in JS
The implementation of the algorithm which adds two number in string form with arithmetic rules.
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3
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1answer
52 views
Finding all backedges in an undirected graph
I have tried to implement the DFS algorithm to find all the back-edges in a graph that lead to a cycle in the graph:
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3
votes
1answer
125 views
Count Acute, Right and Obtuse triangles from n side lengths
Problem Statement: We have \$N\$ sticks. The size of the \$i\$th stick is \$A_i\$. We want to know the number of different types of triangles created with each side from a single different stick. ...
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1answer
79 views
Printing a singly linked list with time complexity O(n) and space complexity O(sqrt(n)) [closed]
My aim is to write a method which prints contents of a singly linked list in reverse order with time complexity \$O(n)\$ and space complexity \$O(\sqrt{n})\$. The best I could come up with is to store ...
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2answers
93 views
Count number of matching nodes in a Binary tree
Problem
Count the number of matching nodes in the subtree rooted at some node n.
Solution
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2answers
187 views
Determining if two strings are anagrams
Two strings are said to be anagrams of each other if the letters of
one string may be rearranged to make the other string. For example,
the words 'elvis' and 'lives' are anagrams.
In this ...
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1answer
85 views
Check if a Binary Tree is full
Problem statement
Given a node check whether the sub-tree rooted at given node is full binary tree or not.
Definition
A full binary tree (sometimes proper binary tree or 2-tree) is a tree in ...
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1answer
71 views
Knights Tour — Something I am doing wrong
I have an assignment to write a knights tour backtracking program in Java where the professor says to:
Eliminate backtracking time by:
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1answer
186 views
How to tweak Tape Equilibrium assignment on Codility to be of complexity O(N)?
Why Codility detects my solution for Tape Equilibrium to have complexity of \$O(n^2)\$. How can I make my code better?
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1answer
337 views
Monitoring the recursive growth of a zombie rabbit population
Breeding like rabbits
Write a function answer(str_S) which, given the base-10 string
representation of an integer \$S\$, returns the largest n such that \$R(...
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1answer
143 views
SQL Permission Handling in WinForms
For my application, I've opted to use Integrated Security with Windows Authentication to access the SQL database. I've created AD security groups for each role and given them ...
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254 views
Finding the shortest excerpt that contains all search terms
Write a function called answer(document, searchTerms) which
returns the shortest snippet of the document, containing all of the
given search terms. The search ...
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2answers
133 views
Finding number of number pairs with given difference [closed]
pairs() is a function which returns the total number of combinations whose difference is k.
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4answers
1k views
Finding the most common character in a string with a hash map
I created a method for finding the most common character in a string (using HashMap):
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0
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1answer
54 views
Summing sub arrays (maximal subarray)
I have this piece of code, and I want to make if the way I'm calculating the time complexity is valid:
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1answer
964 views
Finding the count of negative sub-arrays for a given array
I want to improve my implementation for the following problem:
You are given an array of n integers. A sub-array is "Negative" if sum of all the integers in ...
2
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1answer
71 views
Counting occurrences of sorted elements [closed]
Forgive the hard coded test data - but I'm looking to make the inner while loop disappear, or at least simplified so this code doesn't run in \$O(n^2)\$. I've been thinking over some ideas of how to ...
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2answers
295 views
Google's Python exercise about lists very different from the given solution
Disclaimer: Although I do believe that this is somewhat a code review, I'm not sure if this kind of question applies to the site; if not, please let me know and I'll delete it promptly.
I found ...
3
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1answer
69 views
Prim's minimal spanning algorithm
Is there a way to speed up this code so it is \$O(n^2)\$ instead of \$O(n^3)\$? I'd appreciate if someone showed me how to do so.
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