Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 4911

An algorithm is a sequence of well-defined steps that defines an abstract solution to a problem. Use this tag when your issue is related to design and analysis of algorithms.

2 votes
Accepted

Linear Search Algorithm - Why allow a user to input a start and end index to LS?

Surely, it is not about correctness. It is only a slightly general version of linear search. This technique is not uncommon. Obviously the more general the procedure is, the more applicable it is. Li …
hengxin's user avatar
  • 9,641
1 vote
Accepted

Perform an operation on an array in O(n)

Yes, you can perform this operation in $O(n)$ using a stack $\mathbb{S}$. Before presenting the algorithm directly, I would like to give you an illustration using your example. It is not difficult f …
hengxin's user avatar
  • 9,641
0 votes
Accepted

Finding undirected cycles in linear time (triangulating graphs while minimizing degree)

Which algorithm does "Eulers technique to find an Eulerian cycle" refer to? It probably refers to the Hierholzer algorithm (wiki) which takes linear time. The algorithm below is from the wiki a …
hengxin's user avatar
  • 9,641
4 votes

Solution verification: solving $T(n) = T(n-1) + 2/n$

Although the final result is correct, your solution is not. The recurrences of the form $T(n) = T(n-1) + 2/n$ is often called "decrease and conquer"; while the ones of the form $T(n) = T(n/2) + O(1)$ …
hengxin's user avatar
  • 9,641
3 votes
Accepted

Find the minimum range

Below I try to prove that the greedy algorithm ($\mathcal{A}$) given by @norbertpy (and @Bergi) is correct. Please check it. Problem Definition: The algorithm $\mathcal{A}$ of @norbertpy is for a …
hengxin's user avatar
  • 9,641
1 vote

k-center algorithm in one-dimensional space

[1] Efficient Algorithms for the One-Dimensional $k$-Center Problem. arXiv, 2014. …
hengxin's user avatar
  • 9,641
1 vote
Accepted

Integer Knapsack Problem - No duplicates Allowed

You are right about "independence" between subproblems. Therefore, you use the new subproblems (wiki) by introducing another variable $i$, meaning using the items up to $i$: Define $V[i,s]$ to be …
hengxin's user avatar
  • 9,641
2 votes

Selecting k-1 items that divide a sorted array to k equal parts

I assume that $k = 2^m$ ($m \in \mathbb{N}$) and $k \le n$. Here is a recursive (divide-and-conquer) algorithm: Select the median of the array $A$ and use it to partition the array into $A_l$ and $ …
hengxin's user avatar
  • 9,641
1 vote
2 answers
6k views

Check whether an undirected graph contains a simple cycle of length four using the "Squares"...

The following problem is exercise 4.3 of the book "Algorithms" by S. Dasgupta, C. Papadimitriou, and U. Vazirani. Squares. …
hengxin's user avatar
  • 9,641
2 votes
Accepted

What are some real world examples of nearly sorted lists

What about log files described in AWStats logfile analyzer 7.5 Documentation? An error log file is not always completely sorted but only "nearly" sorted because of cache and writing log engines us …
hengxin's user avatar
  • 9,641
0 votes

How to find the median of 5 elements by rote and its time complexity is O(n)

Becuase $5$ is a constant, you can use (almost) any naive method to find the median of $5$ elements in constant time. However, it is known that $6$ comparisons are sufficient (and necessary) to find …
hengxin's user avatar
  • 9,641
3 votes
Accepted

Given n distinct numbers show that the second smallest element can be found in n + lg n - 2 ...

The algorithm with $n + \lceil \lg n \rceil -2$ comparisons uses "tournament" (lecture note from utdallas). To form a tournament tree: Compare $A[2i−1]$ with $A[2i]$ for $i = 1$ to $n$. We compare t …
hengxin's user avatar
  • 9,641
7 votes

Determine whether a point lies in a convex hull of points in O(logn)

The proofs of these two theorems contain the algorithms you are looking for. …
hengxin's user avatar
  • 9,641
2 votes
0 answers
145 views

Are there some popular science videos on computer algorithms to recommend?

I am seeking for some popular science videos on computer algorithms for my last lecture delivered in this term. … The topic of the videos includes but are limited to algorithm design, algorithm analysis, computational complexity, the application of algorithms, the history of algorithms (even computer science), the …
hengxin's user avatar
  • 9,641
20 votes

log(n) complexity. Difficulty understanding example

Do you know the Harmonic series (wiki)? $$1 + \frac{1}{2} + \cdots + \frac{1}{n} = 1 + \sum_{i=2}^{n} \frac{1}{i} \le 1 + \int_{1}^{n} \frac{1}{x} \text{d}x = 1 + \ln n = \Theta(\log n).$$ Similarly …
hengxin's user avatar
  • 9,641

1
2 3 4 5 6
15 30 50 per page