hash function for string
I’ve had nice results with djb2 by Dan Bernstein.
algorithm
How to calculate big-theta
Can some one provide me a real time example for how to calculate big theta. Is big theta some thing like average case, (min-max)/2? I mean (minimum time – big O)/2 Please correct me if I am wrong, thanks
Algorithm to return all combinations of k elements from n
Art of Computer Programming Volume 4: Fascicle 3 has a ton of these that might fit your particular situation better than how I describe. Gray Codes An issue that you will come across is of course memory and pretty quickly, you’ll have problems by 20 elements in your set — 20C3 = 1140. And if … Read more
Image rotation algorithm
One of the best pages describing image rotation algorithms I’ve found on the internet is tied to Dan Bloomberg’s excellent leptonica library. While the leptonica library itself is written in C and won’t help you, his page on image rotation algorithms: http://www.leptonica.org/rotation.html is definitely worth a read. You will most likely want to implement something … Read more
How to get current time in milliseconds?
Simply use std::chrono. The general example below times the task “of printing 1000 stars”: Instead of printing the stars, you will place your sorting algorithm there and time measure it. Do not forget to enable the optimization flags for your compiler, if you intend to do some benchmarking, e.g. for g++, you need -O3. This is serious, check … Read more
Exactly how many comparisons does merge sort make?
Let’s see if we can work this out! In merge sort, at each level of the recursion, we do the following: Split the array in half. Recursively sort each half. Use the merge algorithm to combine the two halves together. So how many comparisons are done at each step? Well, the divide step doesn’t make … Read more
Weighted random selection from array
Compute the discrete cumulative density function (CDF) of your list — or in simple terms the array of cumulative sums of the weights. Then generate a random number in the range between 0 and the sum of all weights (might be 1 in your case), do a binary search to find this random number in … Read more
Algorithm for solving Sudoku
30 I want to write a code in python to solve a sudoku puzzle. Do you guys have any idea about a good algorithm for this purpose. I read somewhere in net about a algorithm which solves it by filling the whole box with all possible numbers, then inserts known values into the corresponding boxes.From … Read more
How to find maximum spanning tree?
Yes, it does. One method for computing the maximum weight spanning tree of a network G – due to Kruskal – can be summarized as follows. Sort the edges of G into decreasing order by weight. Let T be the set of edges comprising the maximum weight spanning tree. Set T = ∅. Add the … Read more
Creating a maze solving algorithm in Java
You probably should module your program – as I can understand it, you are reading the maze from file and trying to solve it at the same time. A better approach will be to split the program into 2 distinct parts: read the input file and create a matrix with all the data solve the maze from … Read more