permutation

问题 I'm trying to create a permutation of a multidimensional array in classic asp (vbscript) and I'm seriously stuck. I've tried several functions of my own and also tried copying several php versions over, but I often end up with something that either goes into a buffer overflow / infinite recursion or I get results that are more like a combination than a permutation, if I understand the differences correctly. Lets say it's for a shirt. The shirt can have colors, sizes, and styles. (The actual

问题 I want to match strings which begin with all six characters abcdef , regardless of the order in which these six characters occur at the beginning of the string. All six characters must appear once, and once only, in the first six characters of the string, to produce a match. e.g. "dfabce..." is a match, but "aacdef..." is not. Can regular expressions do this, or do I need a parser? 回答1: Sure, you could do this with positive lookahead assertions: ^(?=.{0,5}a)(?=.{0,5}b)(?=.{0,5}c)(?=.{0,5}d)(?

问题 I have an array which contains lets say [25,15,8,20] I want to find all possible arrangements of numbers that is possible. expected output: 25 15 8 20 25 15 20 8 25 20 15 8 25 20 8 15 25 8 20 15 25 8 15 20 15 25 8 20 15 25 20 8 15 20 25 8 15 20 8 25 15 8 20 25 15 8 25 20 20 25 15 8 20 25 8 15 20 8 25 15 20 8 15 25 20 15 25 8 20 15 8 25 8 15 20 25 8 15 25 20 8 25 15 20 8 25 20 15 8 20 15 25 8 20 25 15 void print(int *num, int n) { int i; for ( i = 0 ; i < n ; i++) printf("%d ", num[i]); printf

问题 I need a number of unique random permutations of a list without replacement, efficiently. My current approach: total_permutations = math.factorial(len(population)) permutation_indices = random.sample(xrange(total_permutations), k) k_permutations = [get_nth_permutation(population, x) for x in permutation_indices] where get_nth_permutation does exactly what it sounds like, efficiently (meaning O(N)). However, this only works for len(population) <= 20 , simply because 21! is so mindblowingly

问题 For example, if the input string is “ABC”, then output should be “ABC, ACB, BAC, BCA, CAB, CBA”. Here is my approach : #include<stdio.h> #include<conio.h> #include<string.h> void print(char str[],int visited[],int index,char temp[],int len) { if(index==len) { temp[index]='\0'; printf("\n%s",temp); return; } for(int i=0;i<len;i++) { if(!visited[str[i]-'A']) { visited[str[i]-'A']=1; temp[index]=str[i]; print(str,visited,index+1,temp,len); visited[str[i]-'A']=0; } } } int main() { int visited[20

问题 I have seen other questions about string permutations, but they don't completely cover my question. Suppose I have an array of strings: ["A", "B", "C", "D", "E"] and I am looking for a way to get all possible combinations of for instance three elements: AAA, AAB, AAC, AAD, AAE, ABA, ACA, ... Other solutions for permutations (e.g. here, or here) don't allow the same element to be duplicated, and result in: ABC, ABD, ABE, BAC, ... I now use a brute-force approach, with many iterations, but of

问题 I want to find a combinatorial formula that given a certain number of integers, I can find the number of all possible groupings of these integers (such that all values belong to a single group) Say I have 3 integers, 1, 2, 3 There would be 5 groupings: 1 2 3 1|2|3| 1 2|3 1|2 3 2|1 3 I have calculated these computationally for N = 3 to 11, but I am trying to theoretically assertain. These values are: (I believe they are correct) num_integers num_groupings 3 5 4 15 5 52 6 203 7 877 8 4140 9

问题 Right now I am working on a suite of word games as a means of teaching myself (and recreating some of my favorite word games!) With the help of an 'actual' studied programming friend, we have implemented a nice permutation method in one of my classes. It is finding all permutations from 3 letters and up and comparing them to Lists of strings I have containing what is essentially the Scrabble tournament word list. That's the background, here is my current issue: I now have all of the

问题 Right now I am working on a suite of word games as a means of teaching myself (and recreating some of my favorite word games!) With the help of an 'actual' studied programming friend, we have implemented a nice permutation method in one of my classes. It is finding all permutations from 3 letters and up and comparing them to Lists of strings I have containing what is essentially the Scrabble tournament word list. That's the background, here is my current issue: I now have all of the

问题 I'm doing a base 64 permutation incrementor. I've already written all the working code. But seeing as how Ruby already as Array::permutation which produces an Enumerator; I'd like to use that and take it a step further. Without having to go through every permutation by using 'next', can I set the start point? x = ('A'..'Z').to_a + ('a'..'z').to_a + ('0'..'9').to_a + ['+','/'] y = x.permutation(12) y.peek.join => "ABCDEFGHIJKL" y.next y.peek.join => "ABCDEFGHIJKM" . # DO SOMETHING LIKE THIS y