combinations

问题 I need a function that can solve the following: for a binomial function nCr=k, given r and k find n. in mathematics nCr=n!/r!(n-r)! I tried following but it doesn't solve it. for example 8C6=28, for my function the inputs are 6 and 28 and i want to find 8. This may not have exact integer number so I want to find an x>=n. """I am approaching it this way, i.e. find the solution of a polynomial function iteratively, hope there is a better way""" def find_n(r,k): #solve_for_n_in(n*(n-1)...(n-r)

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed last year . There's another Stack Overflow post that was created for an algorithm related to vehicle registration numbers... According to the entered license plate (eg. ABC123) and a list of replacement values (eg 1 replaced by I). I need to get all possibles combinations. The answer by

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I've created a jquery script that generates all possible combinations of a string, where numbers and lower case letters are involved. I only want strings 10 characters long, so I threw in an if statement

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I need to write a function which finds the possible fixed length combinations of a string. The need is that not all combis are required. For example, if the string is "abcde", and we need combis of length 3, then

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 days ago . permutation of two columns data of table column 1 column 2 1 3 2 4 i need all possible permutations limited to two characters like want result as ho to do as this 12 13 14 21 22 23 24 31 32 33 34 41 42 43 44 all possible sets limited to two characters thanks in php or mysql query

问题 Little challenge. Goal (nodeJS, loop is an * interator function using "yield" strategy) var str; var minChars = 1; var maxChars = 10; for (str of loop('abcdefghijklmnopqrstuvwxyz',minChars,maxChars)) { console.log(str); } Constraints: Only generate string combinations length between minChars and maxChars Must not consumme all memory (Array in store not allowed) Must use ES6 iterators, so step by step is possible Recursion is allowed Can provide billions of combination Sample output (order is

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 3 years ago . I have a data frame as df <- data.frame(x = c(1,2,3,4,5), y = c(11,12,13,14,15)) What I am trying to get is this df 1 11 2 12 3 13 4 14 5 15 2 12 3 13 4 14 5 15 3 13 4 14 5 15 5 15 It basically is all the possible combinations of the data frame. I tried combn and expand.grid but they give me all

问题 I have two vectors vector1 = c(0.9,0.8,0.7,0.6,0.5) vector2 = c(10,20,30) I now want all combinations of the elements in these vectors, while vector2 is used twice. I use expand.grid() to this. combinations = expand.grid(vector1,vector2,vector2) The result is a frame with the columns Var1 , Var2 and Var3 . Now I want to combine the first vector with the second vector with some conditions. E.g. 0.9 to 0.7 from vector1 should only be combined with Var2 >= Var3 . And 0.6 to 0.5 should only be

问题 so I have a data frame containing certain type of data for different stocks, sample as followed: Date RY TD BNS... 10-01 2.98 2.29 1.91 10-02 2.96 2.61 2.15 10-03 2.96 2.59 2.09 ... What I want to do is to use combn() function to calculate the sum of the products of all possible combinations of 2 stocks. I know how to do it with single values using, for example: df <- c(2.98, 2.29, 1.91) sum(combn(df, 2, prod)) But since now I have a data frame with daily data for each symbol, how do I apply

问题 This question already has answers here : How to write combinatorics function in postgres? (2 answers) Closed 2 years ago . Im trying to solve a puzzle, by using some prunning and brute force I reach level 48. But now thinking use some Memoization to reuse the calculations. I have some tables: puzzles: (puzzle_id, level, flips) CONSTRAINT puzzle_id_pk PRIMARY KEY (puzzle_id) puzzle_rows (puzzle_id, row_id, row_flips) CONSTRAINT puzzle_row_pk PRIMARY KEY (puzzle_id, row_id), CONSTRAINT puzzle