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.
2
votes
2answers
64 views
'Zero out' a matrix using Python
Below is my code for an attempted solution to cracking the coding interview exercise 1.8 written in python 3.5. The problem statement is:
Write an algorithm such that if an element in an MxN ...
3
votes
1answer
52 views
Rotate Matrix using Python
This is my solution to Exercise 1.7 from Cracking the Coding Interview. I would appreciate any feedback on coding style and algorithm efficiency.
I do know that there is an existing function in ...
1
vote
2answers
55 views
Simple string compression in Python
This is my solution to exercise 1.6 in Cracking the Coding Interview. I am interested in receiving feedback on the coding style and time/space complexity.
The exercise statement is:
Implement a ...
4
votes
2answers
98 views
Check if two strings are one 'edit' apart using Python
The code below is my solution in python 3 to exercise 1.5 in Cracking the Coding Interview. I would appreciate feedback on both the algorithm (improvements to space and time complexity) and/or coding ...
3
votes
2answers
134 views
Check if a string is a permutation of a palindrome using Python
This is a solution to exercise 1.4 from Cracking the Coding Interview written using Python 3.
Given a string, write a function to check if it is a permutation of a palindrome.
Example: 'Tact Coa'
...
3
votes
3answers
145 views
URLIfy a character array using Python - follow-up
This is a follow up to my last code review:
URLify a string using Python
This problem has been reviewed in other languages, but I tried to solve this without looking at those answers.
I am hoping ...
4
votes
1answer
79 views
URLify a string using Python
I have been working my way through the exercises in the book Cracking the Coding Interview. I wanted to get feedback for the following exercise.
Write a method to replace all spaces in a string ...
5
votes
2answers
726 views
Check if one string is a permutation of another using Python
The code below is an attempt at a solution to an exercise from the book "Cracking the Coding Interview." I believe that the worst case time complexity of the code below is O(n), where n is the length ...
1
vote
1answer
72 views
Stack which finds the minimum element
Write a program to implement stack which implements min a method
which gives the minimum element below the top element in the stack.
...
2
votes
1answer
73 views
Counting all substrings with exactly k distinct characters
Problem Statement : Given a string of lowercase alphabets, count all possible substrings (not necessarily distinct) that has exactly k distinct characters. Example:
Input: abc, k = 2 Output: 2 ...
1
vote
1answer
256 views
0
votes
0answers
40 views
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 ...
2
votes
1answer
95 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 ...
5
votes
2answers
83 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 ...
7
votes
3answers
429 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 ...
11
votes
3answers
277 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:
...
3
votes
2answers
81 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 ...
2
votes
0answers
54 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
votes
1answer
76 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:
...
9
votes
2answers
143 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
votes
1answer
85 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
40 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 ...
3
votes
2answers
50 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 ...
6
votes
6answers
436 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 ...
1
vote
2answers
93 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?
...
-5
votes
1answer
75 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
votes
1answer
84 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 ...
2
votes
2answers
1k 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 ...
1
vote
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 ...
3
votes
0answers
94 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 ...
3
votes
1answer
47 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
votes
1answer
267 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 ...
4
votes
2answers
324 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
votes
1answer
645 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 ...
3
votes
2answers
133 views
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
votes
1answer
60 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?
...
2
votes
0answers
41 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 (...
4
votes
2answers
131 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?
...
2
votes
2answers
214 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 <...
1
vote
3answers
164 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 (...
0
votes
0answers
21 views
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 ...
2
votes
3answers
152 views
Long arithmetic addition in JS
The implementation of the algorithm which adds two number in string form with arithmetic rules.
...
3
votes
1answer
54 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:
...
3
votes
1answer
134 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. ...
1
vote
1answer
92 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 ...
2
votes
2answers
102 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
...
1
vote
2answers
275 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 ...
1
vote
1answer
89 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 ...
4
votes
1answer
72 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:
...
4
votes
1answer
199 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?
...
