New answers tagged algorithm
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Selection algorithms (order statistic) in Java: linear time vs. sorting selector vs. Quickselect
(I'm no fan of final for interfaces and classes, this seems to carry to sealed.)
one alternative to specifying ...
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1
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Unidirectional linked list in C
make sure there are no possible memory leaks
Advice on testing:
Have allocation & disposal functions increasing & decreasing an instance count as ...
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4
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Unidirectional linked list in C
A serious error everybody appears to fix without comment:
push_back() allocates memory and forgets to initialize some of it. Specifically, it fails to write:
...
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3
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Unidirectional linked list in C
Some suggestions follow.
1/ Comment your code. It won't affect at all how the code does its job (unless you do something silly like comment out a vital line of code), but it will affect the ability to ...
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1
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How to using custom colormap with pixel calculation, gray scale value by opencv and make it workable on camera
Looking at just the code, I find it difficult to see its purpose.
In particular, I don't find colormap:
Document your code. In the code.
Define a function for the mapping presented.
Find or define a ...
4
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Unidirectional linked list in C
Interfaces
Consider the work that your contains function does compared to the information it returns.
It finds the first position that has the value in question. ...
5
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Unidirectional linked list in C
You might consider to abbreviate struct node with a typedef name:
...
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11
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Unidirectional linked list in C
Think about the failure cases. For example:
struct node *list = malloc(sizeof(struct node));
list->data = data;
list->next = NULL;
return list;
If ...
- 60.7k
1
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Re-order table columns in HTML dynamically with Javascript
Start with the data in Javascript. Always sort the Javascript, never from the html table. Always create a new table. Throwing away the pre-existing table fantastically simplifies everything.
I ...
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5
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Accepted
Sort array of associative arrays by the key of the subarrays
Short of simplifying your input array structure, using functional sorting will be most direct with array_multisort() which is fed an array of keys to sort in a ...
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3
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Traverse/transform (xml) tree
Consider using a SAX parser
I am trying to write a utility for transforming xml trees using single pass [...]
But you are using a DOM parser library. This means it will parse the whole XML document ...
- 35.7k
3
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Sort array of associative arrays by the key of the subarrays
Bubble sort algorithm - inefficiently implemented
After each iteration of the Bubble sort algorithm "one less element (the last one) is needed to be compared until there are no more elements left ...
- 25.7k
2
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Sort array of associative arrays by the key of the subarrays
I solved it with usort like recommended by @greybeard. Credits to him!
...
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1
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Accepted
Increase efficiency of stick cutting algorithm
Two reviewers advised how to avoid establishing the length of current longest piece from scratch, as that promises worst case run time at least quadratic in the number m of cuts.
In greybeard's ...
3
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Increase efficiency of stick cutting algorithm
Consider time complexity
When the code works but it runs too slow,
it's usually because the algorithm doesn't scale well to larger inputs.
It's good to review the time complexity and look for ...
- 110k
3
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Increase efficiency of stick cutting algorithm
Hm. Interview.
You tried something simple (good!) and it doesn't fit the time frame (pity).
Well, if it seems to work, give it a name and use it as a test for advanced implementations.
Make it a ...
- 4,958
1
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Counting the number of patterns that exist in a particular string
Another way to Simplify the loop logic
(and explicitly avoid using oob indices):
...
- 4,958
1
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Find factors of a Mersenne number
This code is:
Slower than the original (why do you need two loops? why a vector? boolean operations are much faster)
Futile (all factors with 64 bits or smaller, of mersenne numbers with exponents ...
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3
votes
Accepted
General algorithm to calculate sums of all subsets of a given sequence of numbers
This is pretty slick modern C++. I like it.
The recursion depth (equal to the input length) is unlikely to become a problem before the exponential explosion does.
Naming the all the template types ...
- 60.7k
1
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Counting the number of patterns that exist in a particular string
Simplify the loop logic
The nested loop in isSubstr is a bit difficult to understand:
The outer loop variable i can be modified ...
- 110k
0
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Refactoring a binary tree used as a tournament ladder
I'm having a hard time understanding the requirements. I understand what a tournament bracket is, but the teams only get filled in as games are played, so it's not clear what exactly we need to do ...
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4
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Counting the number of patterns that exist in a particular string
Harold gave a good answer addressing the algorithm used. I'll look at other aspects of your code.
You say you have a using namespace std; somewhere because you're ...
- 60.7k
6
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Counting the number of patterns that exist in a particular string
The current time complexity I reckon is O(N*M) where N = elems of pattern, M = elems of word.
I'd say O(NM) where N = the total size (sum of lengths) of patterns, M = length of word. There is a ...
- 6,759
3
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Get all partitions of an array into k non-empty sub-arrays
Time and space complexity
To calculate the time and space complexity,
it's useful to consider the output: what must it contain.
For every way to split into sub-arrays,
the output will contain one ...
- 110k
3
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C++ Binary search using SIMD
Use the same API as std::ranges::lower_bound
You mention that you wanted to use std::ranges algorithms to do a binary search. If ...
- 35.7k
2
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Improving time complexity for codechef Que
This code is quite terrible to read. Please think about what your goal is when you do these code challenges. Is it just to get some site to say "AC" instead of "TLE"? Or is it to ...
- 35.7k
1
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Next level Improved Sieve of Eratosthenes
This is similar to a wheel sieve with basis {2,3,5}.
You can simplify everything and write it compactly like this:
...
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1
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Finding first unique character in string
We forgot to #include <string>.
This definition looks like C:
typedef struct
{
⋮
}
Tracking;
In C++, we ...
- 60.7k
2
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Accepted
Segmentation of list to minimize the largest sum
One could approach this from the goal:
What is the business of a Segmentation instance, what are its business methods? You tagged ...
- 4,958
4
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Accepted
Finding first unique character in string
As already mentioned, you can do this in a one-pass algorithm. You only need to keep track of whether you have seen a character before, and what the position of its first occurence is. Here is a ...
- 35.7k
3
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Finding first unique character in string
Consider a simpler algorithm:
Pass 1: Build a map of counts of characters.
Pass 2: For each index, if the count of the current character is 1, return the index.
If pass 2 terminates without returning,...
- 110k
3
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ReversibleList: a list that is "reversed" in O(1) time
I have only one suggestion: remove the forwardAll() method.
As I understand it, the point of ReversibleList is to allow for ...
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5
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ReversibleList: a list that is "reversed" in O(1) time
Additional Bugs
Your ReversedList has numerous bugs.
The reverse() method does not reverse the list when it is already in ...
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6
votes
Accepted
ReversibleList: a list that is "reversed" in O(1) time
Consider composition over inheritance
Doing inheritance right is very hard.
Keep in mind that subclass coupling (when class A is a subclass of class B) is the strongest type of coupling between two ...
- 110k
16
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ReversibleList: a list that is "reversed" in O(1) time
I don't really like the direction toggling stuff. Mostly on the grounds of disliking state if possible. You could end up with the list pointing in the opposite direction to the one intended.
What I ...
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16
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ReversibleList: a list that is "reversed" in O(1) time
Bug
You have a bug!
a[2:5] = ReversibleList([1, 2, 3])
print(a) # [5, 4, 3, 2, 1, 0]
ReversibleList([1, 2, 3]) is constructing ...
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3
votes
Accepted
Queue using circular linked list
There is a bug in the dequeue function:
// Retrieve the value before deleting the node
int value = node->value;
The ...
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