recursion

问题 I am trying to write a method that uses recursion to compare the strings str1 and str2 and determine which of them comes first alphabetically (i.e., according to the ordering used for words in a dictionary). If str1 comes first alphabetically, the method should return int 1 . If str2 comes first alphabetically, the method should return the int 2 . If the two strings are the same, the method should return the int 0 . I know that there is a compareTo method in the Java API but i would like to

问题 Supposing I had a list as follows: mylist = ['a','b','c','d'] Is it possible to create, from this list, the following dict without using recursion/a recursive function? { 'a': { 'b': { 'c': { 'd': { } } } } } 回答1: For the simple case, simply iterate and build, either from the end or the start: result = {} for name in reversed(mylist): result = {name: result} or result = current = {} for name in mylist: current[name] = {} current = current[name] The first solution can also be expressed as a

问题 I've just started Rust tutorial and ended with such code using recursion extern crate rand; use std::io; use rand::Rng; use std::cmp::Ordering; use std::str::FromStr; use std::fmt::{Display, Debug}; fn try_guess<T: Ord>(guess: T, actual: T) -> bool { match guess.cmp(&actual) { Ordering::Less => { println!("Too small"); false } Ordering::Greater => { println!("Too big"); false } Ordering::Equal => { println!("You win!"); true } } } fn guess_loop<T: Ord + FromStr + Display + Copy>(actual: T)

问题 I have an arraylist of Strings that want to have all possible combinations stored into another collection. For example: [air,bus,car] -> [air] [bus] [car] [air,bus] [air,car] [bus,air] [bus,car] [car,air] [car,bus] [air,bus,car] [air,car,bus] ... [car,bus,air] Repetitions are not important. The code right now I have is: public ArrayList<String> comb(ArrayList<String> wrds, ArrayList<String> str, int size) { ArrayList<String> s = new ArrayList<String>(); s.addAll(str); if(size != a1.size()) {

问题 I am having difficulty conceptualizing a recursive function for appending replies to comments, replies to replies, replies to replies to replies, etc. This is my comments table: Which SHOULD look something like this when rendered: As it stands I can render each comment associated with the article_id (excluding those that are NOT NULL , of course): $comments = $commentClass->fetch_article_comments($article_id); foreach($comments as $comment) { $comment_id = $comment['comment_id']; $member_id =

问题 I'm having difficulty understanding what's going on with The Little Schemer's evens-only*&co example on page 145. Here's the code: (define evens-only*&co (lambda (l col) (cond ((null? l) (col '() 1 0)) ((atom? (car l)) (cond ((even? (car l)) (evens-only*&co (cdr l) (lambda (newl product sum) (col (cons (car l) newl) (opx (car l) product) sum)))) (else (evens-only*&co (cdr l) (lambda (newl product sum) (col newl product (op+ (car l) sum))))))) (else (evens-only*&co (car l) (lambda (newl

问题 I'm currently trying to wrap my head around learning Python and I've come to a bit of a stall on recursive functions. In Think Python, one of the exercises is to write a function that determines if number a is a power of number b using the following definition: "A number, a, is a power of b if it is divisible by b and a/b is a power of b. Write a function called is_power that takes parameters a and b and returns True if a is a power of b." The current state of my function is: def isPower(a,b)

问题 Arrow functions in ES6 do not have an arguments property and therefore arguments.callee will not work and would anyway not work in strict mode even if just an anonymous function was being used. Arrow functions cannot be named, so the named functional expression trick can not be used. So... How does one write a recursive arrow function? That is an arrow function that recursively calls itself based on certain conditions and so on of-course? 回答1: Writing a recursive function without naming it is

问题 Arrow functions in ES6 do not have an arguments property and therefore arguments.callee will not work and would anyway not work in strict mode even if just an anonymous function was being used. Arrow functions cannot be named, so the named functional expression trick can not be used. So... How does one write a recursive arrow function? That is an arrow function that recursively calls itself based on certain conditions and so on of-course? 回答1: Writing a recursive function without naming it is

问题 Arrow functions in ES6 do not have an arguments property and therefore arguments.callee will not work and would anyway not work in strict mode even if just an anonymous function was being used. Arrow functions cannot be named, so the named functional expression trick can not be used. So... How does one write a recursive arrow function? That is an arrow function that recursively calls itself based on certain conditions and so on of-course? 回答1: Writing a recursive function without naming it is