# All Questions

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1answer
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### Generate random matrix and its inverse

I want to randomly generate a pair of invertible matrices $A,B$ that are inverses of each other. In other words, I want to sample uniformly at random from the set of pairs $A,B$ of matrices such that ...
2answers
88 views

### Efficient n-choose-k random sampling

Is there an efficient method of sampling an n-choose-k combination at random (with uniform probability, for example)? I have read this question but it asks for generations of all combinations, not ...
2answers
129 views

### Efficiently shuffling items in $N$ buckets using $O(N)$ space

I’ve run into a challenging algorithm puzzle while trying to generate a large amount of test data. The problem is as follows: We have $N$ buckets, $B_1$ through $B_N$. Each bucket $B_i$ maps to a ...
2answers
53 views

### Limit repetitions in randomized list with each unique element occurring n times

I have a set of 3 elements and need to generate a randomized sequence containing each element n times with the condition that one element can only occur m times in a row. So with elements [0,1,2] n = ...
1answer
65 views

### Sampling from a set of numbers with a fixed sum

Let $s = \{x_1, x_2, \ldots, x_n\}$ be a set of $n$ random non-negative integers where $\sum_i x_i = n$. And let $\{y_1, y_2, \ldots, y_{\sqrt{n}}\}$ denote a subset of size $\sqrt{n}$ of $s$, chosen ...
3answers
244 views

### Is there a random shuffle algorithm using only true /false?

Is there a way to randomly shuffle an array using only a source of random boolean values? SO to clarify, shuffle using true /false only, and not integers or decimals. For this question, I'm ...
1answer
269 views

### Choosing a random bit from a bitmap

Since, I don't have strong algorithmic background my question may sound a litlle odd. Please correct me, if so. I have quite a large bitmap (~100 Million bits) (e.g. ...
1answer
66 views

### How to simulate this randomized “finite” sum? [closed]

Consider the the Geometric Brownian motion $\qquad dX_t=\mu X_t dt+\sigma X_t dW_t$, with $X_0=1$, $\mu=0.2$, and $\sigma=0.30$. for each $n=1,2,3,..$ let $h_n=1/n$, and let $X^n_n$ be the final ...
1answer
156 views

### Random uniform sampling of position restricted permutations

Is there any efficient algorithm which is able to generate nearly uniform samples of permutations in case of position restrictions? Consider $N \times N$ restriction matrices $R$, that is matrices ...
1answer
751 views

### Generate a random graph with geometrical degree distribution

I'm working on graph generation, trying to implement the RT-nested-Smallworld network model described in this paper. We are talking about generating an undirected graph in a slightly different way ...
3answers
2k views

### Constructing a random Hamiltonian Cycle (Secret Santa)

I was programming a little Secret Santa tool for my extended family's gift exchange. We had a few constraints: No recipients within the immediate family Nobody should get who they got last year The ...
1answer
41 views

### Algorithm for random generation of two connected partitions of a finite set [closed]

Given the set $X=\{1,2,\ldots,n\}$; $\,\,$ $n=mp=kq$ where $m,k,p,q$ are positive integers. Please help me to programme an algorithm that realizes random generation of the following two partitions of ...
1answer
407 views

### Is this method really uniformly random?

I have a list and want to select a random item from the list. An algorithm which is said to be random: When you see the first item in the list, you set it as the selected item. When you see ...