combinatorics

I have a list of n words (let's say 26). Now I want to get a list of all possible combinations, but with a maximum of k words per row (let's say 5) So when my word list is: aaa, bbb, ..., zzz I want to get: aaa bbb ... aaabbb aaaccc ... aaabbbcccdddeeefff aaabbbcccdddeeeggg ... I want to make it variable, so that it will work with any n or k value. There should be no word be twice and every combinations needs to be taken (even if there are very much). How could I achieve that? EDIT: Thank you for your answers. It is not an assignment. Is is just that I forgot the combinations of my password

I have two arrays of strings, not necessarily of the same length, I want to find all the possible "sets" of combinations between two values from the arrays, without repeats from either array. For example, given the arrays: { "A1", "A2", "A3" } { "B1", "B2" } The result I want is the following sets: { ("A1", "B1"), ("A2", "B2") } { ("A1", "B1"), ("A3", "B2") } { ("A1", "B2"), ("A2", "B1") } { ("A1", "B2"), ("A3", "B1") } { ("A2", "B1"), ("A3", "B2") } { ("A2", "B2"), ("A3", "B1") } My general direction is to create recursive function that takes as a parameter the two arrays and removes each

I have an array of integers: n[] . Also, I have an array ( Nr[] ) contains n.length integers. I need to generate all combinations of n[] in a following way: /* let n.length == 3 and Nr[0] = 2, Nr[1] = 3, Nr[2] = 3 */ n = {0, 0, 0}; n = {1, 0, 0}; n = {2, 0, 0}; n = {0, 1, 0}; n = {0, 2, 0}; n = {0, 3, 0}; n = {0, 0, 1}; ... n = {1, 1, 0}; n = {1, 2, 0}; n = {1, 3, 0}; n = {2, 1, 0}; n = {2, 2, 0}; n = {2, 3, 0}; n = {1, 1, 1}; ... n = {0, 1, 1}; // many others The goal is to find all combinations of n , where n[i] can be 0 to Nr[i] . I did not succeed... How to solve it in Java? Or not in Java

Composition of n into k parts - I want to list all the possible compositions of n into k parts - does anyone have an algorithm (preferably in R)? Or know if it's in library anywhere? For example, if I have n cubes, and k bags, and want to list all the possible arrangements of the cubes in the bags. e.g. there are 3 ways you can arrange 2 cubes into 2 bags: (2, 0) (1, 1) (0, 2) I've found the NEXCOM alogarithm. I've found a version of it here (page 46) in Fortran, but don't code in Fortran so really understand what's going on - any help? What you are attempting to list is called an k

I just came across with this interesting question from my colleague. I'm trying now, but meanwhile I thought I could share it here. With the password grid shown in the Android home screen, how many valid passwords are possible? min password length: 4 max: 9 (correct me if I'm wrong) Dante May Code Summary The full combinations of 4 to 9 distinctive numbers, minus the combinations which include invalid "jump"s. The Long Version The rule for Android 3x3 password grid: one point for once cannot "jump" over a point The author of the original post used Mathematica to generate all 985824

I recently did studying stuff and meet up with Donald Knuth. But i didn't found the right algorithm to my problem. The Problem We have a league with n players. every week they have a match with one other. in n-1 weeks every team fought against each other. there are n/2 matches a day. but one team can only fight once in a week. if we generate an (n/k) combination we get all of the combinations... (assuming k = 2) but i need to bring them in the right order. My first suggestion was... not the best one. i just made an array, and then let the computer try if he finds the right way. if not, go back